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  • 1.
    André, Benny
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Nanocomposites for Use in Sliding Electrical Contacts2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this thesis nanocomposite materials for use in high performance electrical contacts are tested. Self mating silver as coatings on cupper substrates are the most used material combination in power connectors today. In this work two new concepts were tested. The first one was to change one of the mating surfaces to a hard thin coating and keep the other surface made of silver. Tested coatings were nanocomposites with hard carbides in a matrix of amorphous carbon. TiC/a-C and  Ti-Ni-C/a-C were tested both electrically and tribologically. The total amount of carbon and the amount of carbon matrix was important, both for the electrical and the tribological properties. The Ti-Ni-C coating also showed that substituting Ti in TiC with the weak carbide former Ni changed the stability of the carbides. The substitution resulted in more a-C matrix and less C in the carbides. Thin coatings of nc-TiC/a-C and  Ti-Ni-C/a-C showed high potential as material candidates for use in electrical contacts.

    The other tested concept was to modify the used silver instead of replacing it. This was done by embedding nanoparticles of solid lubricant IF-WS2 in the silver. The results from reciprocating sliding displayed low friction and high wear resistance. The modified silver surfaces lasted for 8000 strokes with a friction of about 0.3 while at the same time allowing for a low contact resistance. The results for surfaces of pure silver coating displayed a friction of 0.8-1.2 and that the silver was worn through already after 300 strokes.

    A new method to investigate inherent hardness and residual stress of thin coatings, on complex geometries or in small areas, was also developed. An ion beam was used to create stress free coating as free standing micro pillars. Hardness measured on the pillars and on as-deposited coating were then used to calculate the residual stress in the coatings.

    Delarbeid
    1. Industrialisation Study of Nanocomposite nc-TiC/a-C Coatings for Electrical Contact Applications
    Åpne denne publikasjonen i ny fane eller vindu >>Industrialisation Study of Nanocomposite nc-TiC/a-C Coatings for Electrical Contact Applications
    Vise andre…
    2009 (engelsk)Inngår i: Plasma Processes and Polymers, ISSN 1612-8850, Vol. 6, nr S1, s. S928-S934Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Nanocomposite nc-TiC/a-C coatings were prepared by non-reactive magnetron sputtering in industrial scale equipment, under varying deposition conditions in order to investigate upscaling and possible industrialisation. The coatings were found to have similar microstructure and performance compared to previous laboratory scale experiments. The samples were characterised with XRD, XPS and SEM as well with ball-on-disc, nanoindentation and electrical measurements. Coatings containing a small fraction of a-C matrix phase were found to have promising both electrical properties (rho < 400 mu Omega cm and contact resistances down to 0.34 m Omega at 40 N) and tribological properties (f < 0.3 for 10 000 laps).

    sted, utgiver, år, opplag, sider
    WILEY-VCH Verlag GmbH & Co, 2009
    Emneord
    conductivity, inorganic materials, nanocomposites, thin films, tribology
    HSV kategori
    Forskningsprogram
    Oorganisk kemi; Kemi med inriktning mot oorganisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-109022 (URN)10.1002/ppap.200932303 (DOI)000272302900178 ()
    Tilgjengelig fra: 2009-10-07 Laget: 2009-10-07 Sist oppdatert: 2016-04-14
    2. Synthesis, structure and properties of Ni-alloyed TiCx-based thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Synthesis, structure and properties of Ni-alloyed TiCx-based thin films
    Vise andre…
    2010 (engelsk)Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 20, nr 28, s. 5950-5960Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    By using non-reactive sputter deposition at low temperatures metastable solid solution phases in the Ti–Ni–C system were synthesized. Produced thin films were either single phase carbides or nanocomposite of nanocrystalline carbide and amorphous C. In the Ni-containing samples a supersaturated solid solution phase (Ti1−xNix)Cy was identified, and was present either as single phase or in a nanocomposite with amorphous C. By modification of the chemical stability of the carbide phase, the addition of Ni was found to strongly promote the formation of amorphous carbon phase in the coatings. Samples have been microstructurally analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Mechanical properties have been evaluated through nanoindentation and pin-on-disc measurements; electrical properties were determined by measurement of the resistivity and the contact resistance. Alloyed nanocomposite coatings were also found to exhibit enhanced tribological and electrical properties, with a decreased resistivity and friction. This makes these thin films very interesting for application in sliding electrical contacts. The mechanisms responsible for the reductions remain to be determined.

    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot oorganisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-109034 (URN)10.1039/c0jm00592d (DOI)000279565900025 ()
    Tilgjengelig fra: 2009-10-08 Laget: 2009-10-08 Sist oppdatert: 2017-12-13bibliografisk kontrollert
    3. Friction and contact resistance of nanocomposite Ti-Ni-C coatings
    Åpne denne publikasjonen i ny fane eller vindu >>Friction and contact resistance of nanocomposite Ti-Ni-C coatings
    2011 (engelsk)Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, nr 9-10, s. 555-566Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Ceramic nanocomposite coatings in the Ti-Ni-C were deposited using PVD and studied with respect to tribological properties and contact resistance. It was shown that coatings could be deposited combining of a low contact resistance and a low friction coefficient against silver, making them suitable for use in high performance electrical contacts.Nine coatings with different amounts of C and Ni were deposited. Coatings on flat Ni plated copper substrates were tested in a tribological ball-on-disc setup against ball bearing steel balls. Depending on primarily the amount of carbon the coatings showed very different friction coefficient and wear rate. The coatings were also deposited on cylindrical Ni plated copper substrates. Using geometrically identical silver plated cylinders as counter surface these were evaluated in a test setup better resembling a real life electrical contact. For most coatings a low electrical contact resistance was measured. The evolution of friction coefficient and contact resistance was correlated to wear marks and contact tracks, with their generated tribofilms, as examined after testing using electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy.

    Emneord
    TiC, TiNiC, Friction, Tribofilm, Electrical contacts, Contact resistance
    HSV kategori
    Forskningsprogram
    Oorganisk kemi; Teknisk fysik med inriktning mot materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-109425 (URN)10.1016/j.wear.2010.12.006 (DOI)000290132500001 ()
    Tilgjengelig fra: 2009-10-15 Laget: 2009-10-15 Sist oppdatert: 2017-12-12
    4. Nanoindentation on micro pillars for determination of intrincic hardness and residual stress in coatings deposited on complex geometries
    Åpne denne publikasjonen i ny fane eller vindu >>Nanoindentation on micro pillars for determination of intrincic hardness and residual stress in coatings deposited on complex geometries
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    nanoindentation, hardness, residual stress, focused ion beam, coating, PVD
    HSV kategori
    Forskningsprogram
    Materialvetenskap; Teknisk fysik med inriktning mot tribomaterial; Teknisk fysik med inriktning mot materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-160807 (URN)
    Tilgjengelig fra: 2011-10-31 Laget: 2011-10-31 Sist oppdatert: 2016-04-22
    5. Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles
    Åpne denne publikasjonen i ny fane eller vindu >>Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles
    2012 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, nr 8-9, s. 2325-2329Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A new tribological coating with potential as a coating for components for low-friction applications is tested and compared to three, state of the art, commercial low-friction PVD coatings. The new coating is an electrodeposited coating composed by a Ni-P matrix incorporating fullerene like nanoparticles of WS2. The performance of the new coating is compared with three reference coatings in a ball-on-disc setup. The tribological tests involved ball bearing steel balls slid on coated discs, under different conditions of humidity and also with or without oil lubrication. Both mating surfaces were closely investigated in a scanning electron microscope and the low-friction tribofilms formed were further analysed. The correlations found between coefficient of friction, surface roughness of the wear scar, tribofilm formation and contact conditions are discussed. The new coating exhibits a very low coefficient of friction at low humidity, a behaviour closely resembling that of the MoS2-based commercial reference, whereas the carbon based PVD coatings tested exhibit the reversed dependence of humidity. The low-friction behaviour of the new coating is correlated to the formation of a WS2 tribofilm with a superficial alignment of the basal planes parallel to the sliding direction. When lubricated with a base oil, the beneficial tribofilm is not formed and the coefficient of friction is much higher. The results show that even though the coating is an electrodeposited coating it can compete with state of the art commercial PVD coatings.

    Emneord
    Friction, Wear, Tungsten disulphide, Nanoparticles, Fullerene, Tribofilm
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot tribomaterial; Teknisk fysik med inriktning mot materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-160806 (URN)10.1016/j.surfcoat.2011.10.012 (DOI)000300458500038 ()
    Tilgjengelig fra: 2011-10-31 Laget: 2011-10-31 Sist oppdatert: 2017-12-08
    6. Enhancing silver through embedding of fullerene like WS2 for sliding electrical contacts
    Åpne denne publikasjonen i ny fane eller vindu >>Enhancing silver through embedding of fullerene like WS2 for sliding electrical contacts
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    friction, wear, electrical, contacts, tungsten, disulfide, silver
    HSV kategori
    Forskningsprogram
    Materialvetenskap; Teknisk fysik med inriktning mot materialvetenskap; Teknisk fysik med inriktning mot tribomaterial
    Identifikatorer
    urn:nbn:se:uu:diva-160808 (URN)
    Tilgjengelig fra: 2011-11-01 Laget: 2011-11-01 Sist oppdatert: 2012-05-08
  • 2.
    André, Benny
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kassman-Rudolphi, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Enhancing silver through embedding of fullerene like WS2 for sliding electrical contactsManuskript (preprint) (Annet vitenskapelig)
  • 3.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Multifunctional Carbon Foams by Emulsion Templating: Synthesis, Microstructure, and 3D Li-ion Microbatteries2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Carbon foams are among the existing electrode designs proposed for use in 3D Li-ion microbatteries. For such electrodes to find applications in practical microbatteries, however, their void sizes, specific surface areas and pore volumes need be optimized. This thesis concerns the synthesis of highly porous carbon foams and their multifunctional applications in 3D microbatteries. The carbon foams are derived from polymers that are obtained by polymerizing high internal phase water-in-oil emulsions (HIPEs).

    In general, the carbonization of the sulfonated polymers yielded hierarchically porous structures with void sizes ranging from 2 to 35 µm and a BET specific surface area as high as 630 m2 g-1. Thermogravimetric and spectroscopic evidence indicated that the sulfonic acid groups, introduced during sulfonation, transformed above 250 oC to thioether (-C-S-) crosslinks which were responsible for the thermal stability and charring tendency of the polymer precursors. Depending on the preparation of the HIPEs, the specific surface areas and void-size distributions were observed to vary considerably. In addition, the pyrolysis temperature could also affect the microstructures, the degree of graphitization, and the surface chemistry of the carbon foams.

    Various potential applications were explored for the bespoke carbon foams. First, their use as freestanding active materials in 3D microbatteries was studied. The carbon foams obtained at 700 to 1500 oC suffered from significant irreversible capacity loss during the initial discharge. In an effort to alleviate this drawback, the pyrolysis temperature was raised to 2200 oC. The resulting carbon foams were observed to deliver high, stable areal capacities over several cycles. Secondly, the possibility of using these structures as 3D current collectors for various active materials was investigated in-depth. As a proof-of-concept demonstration, positive active materials like polyaniline and LiFePO4 were deposited on the 3D architectures by means of electrodeposition and sol-gel approach, respectively. In both cases, the composite electrodes exhibited reasonably high cyclability and rate performance at different current densities. The syntheses of niobium and molybdenum oxides and their potential application as electrodes in microbatteries were also studied. In such applications, the carbon foams served dual purposes as 3D scaffolds and as reducing reactants in the carbothermal reduction process. Finally, a facile method of coating carbon substrates with oxide nanosheets was developed. The approach involved the exfoliation of crystalline VO2 to prepare dispersions of hydrated V2O5, which were subsequently cast onto CNT paper to form oxide films of different thicknesses.

    Delarbeid
    1. Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Åpne denne publikasjonen i ny fane eller vindu >>Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Vise andre…
    2016 (engelsk)Inngår i: ChemistrySelect, ISSN 2365-6549, Vol. 1, nr 4, s. 784-792Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

    Emneord
    Emulsion-templated polymer, sulfonation, pyrolysis, spectroscopy, carbon foam
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-283174 (URN)10.1002/slct.201600139 (DOI)000395395900026 ()
    Prosjekter
    3D microbatteries
    Tilgjengelig fra: 2016-04-11 Laget: 2016-04-11 Sist oppdatert: 2017-10-30bibliografisk kontrollert
    2. Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    Åpne denne publikasjonen i ny fane eller vindu >>Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    2013 (engelsk)Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 1, nr 44, s. 13750-13758Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    High surface area carbon foams were prepared and characterized for use in 3D structured batteries. Twopotential applications exist for these foams: firstly as an anode and secondly as a current collector supportfor electrode materials. The preparation of the carbon foams by pyrolysis of a high internal phase emulsionpolymer (polyHIPE) resulted in structures with cage sizes of 25 mm and a surface area enhancement pergeometric area of approximately 90 times, close to the optimal configuration for a 3D microstructuredbattery support. The structure was probed using XPS, SEM, BET, XRD and Raman techniques; revealingthat the foams were composed of a disordered carbon with a pore size in the <100 nm range resultingin a BET measured surface area of 433 m2 g-1. A reversible capacity exceeding 3.5 mA h cm2 at acurrent density of 0.37 mA cm-2 was achieved. SEM images of the foams after 50 cycles showed thatthe structure suffered no degradation. Furthermore, the foams were tested as a current collector bydepositing a layer of polyaniline cathode over their surface. High footprint area capacities of500 mA h cm-2 were seen in the voltage range 3.8 to 2.5 V vs. Li and a reasonable rate performancewas observed.

    sted, utgiver, år, opplag, sider
    United Kingdom: , 2013
    Emneord
    Carbon foam, High internal phase emulsion polymer, microbattery, 3D microbattery, Lithium ion
    HSV kategori
    Forskningsprogram
    Materialvetenskap; Kemi; Materialvetenskap; Fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-210659 (URN)10.1039/C3TA12680C (DOI)000326463400009 ()
    Prosjekter
    STEM-VR-Microbattery
    Forskningsfinansiär
    Swedish Energy AgencySwedish Research Council
    Tilgjengelig fra: 2013-11-12 Laget: 2013-11-12 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    3. Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    Åpne denne publikasjonen i ny fane eller vindu >>Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    carbon, foam, graphitic, anode, three-dimensional, microbattery, lithium
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-312893 (URN)
    Forskningsfinansiär
    Swedish Research Council, 2012–4681StandUp
    Tilgjengelig fra: 2017-01-14 Laget: 2017-01-14 Sist oppdatert: 2017-12-30
    4. Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Åpne denne publikasjonen i ny fane eller vindu >>Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Vise andre…
    2014 (engelsk)Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 15, s. 8804-8813Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

    sted, utgiver, år, opplag, sider
    Royal Society of Chemistry: , 2014
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-228630 (URN)10.1039/C4NR01682C (DOI)000339861500051 ()
    Prosjekter
    STEM-VR-Microbattery
    Tilgjengelig fra: 2014-07-18 Laget: 2014-07-18 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    5. Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    Åpne denne publikasjonen i ny fane eller vindu >>Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    niobium, oxide, nanoparticle, power, energy, carbon, foam, lithium, microbattery
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-312894 (URN)
    Prosjekter
    3D Lithium-ion microbattery
    Forskningsfinansiär
    Swedish Research Council, 2012–4681StandUp
    Tilgjengelig fra: 2017-01-14 Laget: 2017-01-14 Sist oppdatert: 2017-12-30
    6. A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Åpne denne publikasjonen i ny fane eller vindu >>A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Vise andre…
    2016 (engelsk)Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 46, s. 17988-18001Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

    Emneord
    2D materials, vanadium oxides, free-standing, battery, lithium
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-311357 (URN)10.1039/C6TA06571F (DOI)000388505400010 ()
    Forskningsfinansiär
    Swedish Research Council, 2012-4681Swedish Energy AgencyBerzelii Centre EXSELENTStandUp
    Tilgjengelig fra: 2016-12-24 Laget: 2016-12-24 Sist oppdatert: 2017-12-30
  • 4.
    Asfaw, Habtom
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuskript (preprint) (Annet vitenskapelig)
  • 5.
    Bayrak Pehlivan, İlknur
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Functionalization of polymer electrolytes for electrochromic windows2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Saving energy in buildings is of great importance because about 30 to 40 % of the energy in the world is used in buildings. An electrochromic window (ECW), which makes it possible to regulate the inflow of visible light and solar energy into buildings, is a promising technology providing a reduction in energy consumption in buildings along with indoor comfort. A polymer electrolyte is positioned at the center of multi-layer structure of an ECW and plays a significant role in the working of the ECW.

    In this study, polyethyleneimine: lithium (bis(trifluoromethane)sulfonimide (PEI:LiTFSI)-based polymer electrolytes were characterized by using dielectric/impedance spectroscopy, differential scanning calorimetry, viscosity recording, optical spectroscopy, and electrochromic measurements.

    In the first part of the study, PEI:LiTFSI electrolytes were characterized at various salt concentrations and temperatures. Temperature dependence of viscosity and ionic conductivity of the electrolytes followed Arrhenius behavior. The viscosity was modeled by the Bingham plastic equation. Molar conductivity, glass transition temperature, viscosity, Walden product, and iso-viscosity conductivity analysis showed effects of segmental flexibility, ion pairs, and mobility on the conductivity. A connection between ionic conductivity and ion-pair relaxation was seen by means of (i) the Barton-Nakajima-Namikawa relation, (ii) activation energies of the bulk relaxation, and ionic conduction and (iii) comparing two equivalent circuit models, containing different types of Havriliak-Negami elements, for the bulk response.

    In the second part, nanocomposite PEI:LiTFSI electrolytes with SiO2, In2O3, and In2O3:Sn (ITO) were examined. Adding SiO2 to the PEI:LiTFSI enhanced the ionic conductivity by an order of magnitude without any degradation of the optical properties. The effect of segmental flexibility and free ion concentration on the conduction in the presence of SiO2 is discussed. The PEI:LiTFSI:ITO electrolytes had high haze-free luminous transmittance and strong near-infrared absorption without diminished ionic conductivity. Ionic conductivity and optical clarity did not deteriorate for the PEI:LiTFSI:In2O3 and the PEI:LiTFSI:SiO2:ITO electrolytes.

    Finally, propylene carbonate (PC) and ethylene carbonate (EC) were added to PEI:LiTFSI in order to perform electrochromic measurements. ITO and SiO2 were added to the PEI:LiTFSI:PC:EC and to a proprietary electrolyte. The nanocomposite electrolytes were tested for ECWs with the configuration of the ECWs being plastic/ITO/WO3/polymer electrolyte/NiO (or IrO2)/ITO/plastic. It was seen that adding nanoparticles to polymer electrolytes can improve the coloring/bleaching dynamics of the ECWs.

    From this study, we show that nanocomposite polymer electrolytes can add new functionalities as well as enhancement in ECW applications.

    Delarbeid
    1. PEI-LiTFSI electrolytes for electrochromic devices: Characterization by differential scanning calorimetry and viscosity measurements
    Åpne denne publikasjonen i ny fane eller vindu >>PEI-LiTFSI electrolytes for electrochromic devices: Characterization by differential scanning calorimetry and viscosity measurements
    Vise andre…
    2010 (engelsk)Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 94, nr 12, s. 2399-2404Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Polymer electrolytes containing poly(ethylene imine) (PEI) and lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) can serve as model electrolytes for electrochromic devices. Such electrolytes were characterized by differential scanning calorimetry, conductivity, and viscosity measurements. The glass transition temperature (T-g) and viscosity of the PEI-LiTESI electrolytes have minima at a [N]:[Li] ratio of 100:1. Both T-g and viscosity increased at high salt concentrations. The temperature dependences of ionic conductivity and viscosity followed an Arrhenius equation with parameters depending only weakly on the salt concentration. The fluid behavior of the electrolytes could be reconciled with the Bingham plastic model with parameters being functions of salt concentration.

    Emneord
    Polymer electrolyte, Electrochromic, Smart window, PEI, DSC, Viscosity
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-135307 (URN)10.1016/j.solmat.2010.08.025 (DOI)000283959500066 ()
    Tilgjengelig fra: 2011-09-21 Laget: 2010-12-06 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    2. Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
    Åpne denne publikasjonen i ny fane eller vindu >>Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
    Vise andre…
    2011 (engelsk)Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 201-206Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Ionic conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70◦C and molar ratios of 20:1 and 400:1. The electrolytes were characterized by impedance spectroscopy, differential scanning calorimetry, and viscosity measurements. At room temperature, the maximum conductivity was 2×10−6 S/cm at a molar ratio of 50:1. The molar conductivity of the electrolytes displayed first a minimum and then a maximum upon increasing salt concentration. A proportionality of molar conductivity to segmental mobility was seen from glass transition temperature and viscosity measurements. Analysis of the Walden product and isoviscosity conductivity showed that the percentage of ions bound in ion pairs increased at low concentrations below 0.1 mol/kg. The average dipole moment decreased with salt concentration. The temperature dependence of the ionic conductivity showed an Arrhenius behavior.

    Emneord
    Ionic conductivity, Poly (ethylene imine), Arrhenius behavior, Walden rule, Ion pairing
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot polymerkemi; Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-163443 (URN)10.1016/j.electacta.2011.04.040 (DOI)000298463900029 ()
    Tilgjengelig fra: 2011-12-12 Laget: 2011-12-12 Sist oppdatert: 2017-12-08bibliografisk kontrollert
    3. Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
    Åpne denne publikasjonen i ny fane eller vindu >>Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
    Vise andre…
    2010 (engelsk)Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, nr 7, s. 074102-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Polymer electrolytes containing polyethyleneimine and different concentrations of lithium bis(trifluoromethylsulfonyl) imide were investigated by impedance spectroscopy at different temperatures. Two equivalent circuit models were compared for the bulk impedance response. The first one includes a conductive Havriliak-Negami (HN) element which represents ionic conductivity and ion pair relaxation in a single process, and the second model includes a dielectric HN element, which represents ion pair relaxation, in parallel with ion conductivity. Comparison of the two circuit models showed that the quality of the fit was similar and in some cases better for the conductive model. The experimental data follow the Barton-Nakajima-Namikawa relation, which relates the ion conductivity and the parameters of the relaxation. This indicates that ion conductivity and ion pair relaxation are two parts of the same process and should be described by the conductive model.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-133611 (URN)10.1063/1.3490133 (DOI)000283222200101 ()
    Tilgjengelig fra: 2011-09-21 Laget: 2010-11-11 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    4. [PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes: Ion conduction and optical properties
    Åpne denne publikasjonen i ny fane eller vindu >>[PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes: Ion conduction and optical properties
    Vise andre…
    2012 (engelsk)Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 98, s. 465-471Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Ion conductivity and optical properties were investigated for polymer electrolytes based on poly (ethyleneimine) and lithium bis(trifluoromethylsulfonyl)imide and also containing up to 9 wt.% of 7-nm-diameter SiO2 nanoparticles. The [N]:[Li] molar ratio was kept constant at 50:1. Impedance measurements were performed in the frequency range 10(-2)-10(7) Hz and between the temperatures 20 and 70 degrees C with an applied ac voltage of 1 V. Spectrophotometric data of total and diffuse transmittance were taken between the wavelengths 300 and 2500 nm. The bulk impedance was fitted to a conductive Havriliak-Negami circuit model. The ion conductivity increased monotonically for increasing SiO2 contents: specifically its room temperature value went from 8.5 x 10(-7) S/cm without nanoparticles to 3.8 x 10(-5) S/cm for 8 wt.% of SiO2 while the diffuse transmittance remained at similar to 1% so that optical clarity prevailed.

    Emneord
    Polymer electrolyte, Nanocomposite, PEI, LiTFSI, SiO2
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-171404 (URN)10.1016/j.solmat.2011.11.021 (DOI)000300536500065 ()
    Tilgjengelig fra: 2012-03-20 Laget: 2012-03-19 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    5. Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica
    Åpne denne publikasjonen i ny fane eller vindu >>Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica
    2014 (engelsk)Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 119, s. 164-168Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-204451 (URN)10.1016/j.electacta.2013.12.032 (DOI)000335877000023 ()
    Tilgjengelig fra: 2013-08-05 Laget: 2013-08-05 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    6. A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
    Åpne denne publikasjonen i ny fane eller vindu >>A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
    Vise andre…
    2012 (engelsk)Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, nr 24, s. 241902-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Chemically prepared similar to 13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneiminelithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This type of polymer electrolyte is of large interest for opto-ionic devices such as laminated electrochromic smart windows.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-178647 (URN)10.1063/1.4728994 (DOI)000305269200024 ()
    Tilgjengelig fra: 2012-08-02 Laget: 2012-08-01 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    7. Electrochromic Devices with Polymer Electrolytes Functionalized by SiO2 and In2O3:Sn Nanoparticles: Rapid Coloring/Bleaching Dynamics and Strong Near-Infrared Absorption
    Åpne denne publikasjonen i ny fane eller vindu >>Electrochromic Devices with Polymer Electrolytes Functionalized by SiO2 and In2O3:Sn Nanoparticles: Rapid Coloring/Bleaching Dynamics and Strong Near-Infrared Absorption
    Vise andre…
    2014 (engelsk)Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 126, s. 241-247Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We studied the optical properties and coloring/bleaching dynamics of electrochromic devices based on tungsten oxide and nickel oxide and incorporating polymer electrolytes functionalized by adding about one percent of nanoparticles of SiO2 (fumed silica) or In2O3:Sn. SiO2 improved the coloring/bleaching dynamics and In2O3:Sn quenched the near-infrared transmittance. Both of these effects can be important in electrochromic smart windows, and our results point at the advantage of a polymer laminated construction over a monolithic one.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-204448 (URN)10.1016/j.solmat.2013.06.010 (DOI)000338395100035 ()
    Konferanse
    10th International Meeting on Electrochromism (IME), Holland, MI, August 12-16, 2012
    Tilgjengelig fra: 2013-08-05 Laget: 2013-08-05 Sist oppdatert: 2017-12-06bibliografisk kontrollert
  • 6.
    Bojestig, Eric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Adhesion of CVD coatings on new cemeted carbides2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Steel turning inserts cemented carbides have a binder phase consisting of cobalt (Co). However, in recent years a study from the United States National Toxicity Program (NTP) found that cobalt powder is carcinogenic upon inhalation. The European Union's REACH have therefore also classified cobalt powder as carcinogenic upon inhalation. The worldwide search to find a replacement has therefore lately intensified. It is important that the alternative binder phase has no negative effects on the properties of the insert. In this thesis the adhesion between a multilayer ceramic chemical vapor deposition (CVD) coating and a cemented carbide with the alternative binder phases consisting of iron (Fe), nickel (Ni) and cobalt (Co) has been studied.

    First of all, the fracture surfaces showed that the CVD coating was able to grow on all cemented carbides, regardless of which binder phase. To evaluate the adhesion, scratch tests were performed on all samples. The results from the scratch tests were not as expected. No chipping of the coating down to the cemented carbide occurred on any of the samples and the samples with the hardest cemented carbide did not get the highest critical load, which it should according to the literature if all other parameters were the same. Instead the sample with the binder phase consisting of 73 wt% iron and 27 wt% nickel had the highest critical load. This is thought to be due to that during the scratch test the binder phase in this cemented carbide would most likely transform into deformation martensite.

  • 7.
    Borg, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    New Impact test method for rock drill inserts2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This work has been performed at the Applied Materials ScienceDivision at The Ångström Laboratory in collaboration with SandvikMining AB. The project is part of the joint research programmeCoFree.In this work, the problem of finding an impact test method forcemented carbide rock drill inserts is considered. A suitable testmethod is required to benchmark alternative binder cemented carbidesagainst today’s cobalt based grades. The developed test method isbased on a Charpy pendulum arrangement and utilizes, as in rockdrilling, impact of cylindrical bars to achieve the high impact forcesufficient to fracture the rock drill inserts. The impact issymmetrical with two inserts facing each other, which proves to be anefficient way of damaging the inserts. To gain more informationregarding the force and pulse duration, the history of the impact isrecorded with the use of strain gauges. The measured force curvesfrom repeated tests are typically very similar, a strong indicationthat the test loads the buttons in a well-defined, repeatable way.Also, quasi-static loading of the insert is present in the impactwhich agrees to the results from a static compression test. Thisindicates that the inserts are subjected to quasi-static loading,rather than dynamic loading.A single impact test procedure was developed in this work. Thismethodology proved capable of differentiating the impact performanceof two different button cemented carbide grades. Hence, the test canbe used in the future as a benchmark test. It is however necessary toobtain statistical evidence. The impact performance was measured byobserving cracks produced in the impact contact zone with the aid ofan optical microscope with 85x objective. Radial cracks are veryoften found, often forming a cross around the contact zone. Whenlarge button chippings occur due to the impact loading, a very clearsudden drop in the measured force pulse is seen. This is however notseen for impacts that only produces cracks.

  • 8.
    Chatterjee, Sanjukta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Structural and Physical Effects of Carbon Nanofillers in Thermoplastic and Thermosetting Polymer Systems2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Ever since the discovery of carbon nano materials like carbon nanotube (CNT) and graphene, this class of materials has gained significant attention due to their exotic properties. The principle idea of my present research project is to understand the novel improvements induced in polymer matrices with inclusion of the nanofillers. This thesis is thematically divided into three parts.

    In the first part we introduce principle materials that we use for preparation of composites. Methods of nanofiller preparation and different nanocomposites as previously reported in literature are discussed to formulate the basis of our study. Different dispersion techniques are discussed which facilitate uniform nanofiller distribution. A variety of experimental methods are described which were employed to investigate the structure and properties of the composites.

    In the second part we discuss in details polyamide-12 (PA12) composites using CNT and graphene as fillers. A marked improvement is recorded in the toughness of the films with incorporation of CNT, dispersed in PA12 using a surfactant. Electrical percolation is also achieved in the otherwise insulating matrix. With PA-12 fibers we explored the effect of fiber processing and CNT incorporation in the mechanical properties. Extensive wide angle x-ray diffraction was carried out to interpret the structural modifications brought about by CNT in the matrix.

    The final part of the thesis deals with a thermosetting polymer, epoxy composites. CNT, Graphene and also a mixture of the two nanofillers were used as reinforcing agents. Appreciable improvement was recorded in the mechanical properties, electrical and thermal conductivity of the composites. Detailed optical and electron microscopy was carried out to get a vivid idea of the micro-structure and dispersion.

    The presented work demonstrates the significant ability of carbon nanofillers to reinforce polymer matrices enhancing their mechanical, electrical and thermal properties and opening a wide horizon for a variety of applications.

    Delarbeid
    1. Improvement of toughness and electrical properties of epoxy composites with carbon nanotubes prepared by industrially relevant processes
    Åpne denne publikasjonen i ny fane eller vindu >>Improvement of toughness and electrical properties of epoxy composites with carbon nanotubes prepared by industrially relevant processes
    Vise andre…
    2011 (engelsk)Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 22, nr 12, s. 125702-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The addition of carbon nanotubes (CNTs) to polymeric matrices or master batches has thepotential to provide composites with novel properties. However, composites with a uniformdispersion of CNTs have proved to be difficult to manufacture, especially at an industrial scale.This paper reports on processing methods that overcome problems related to the control andreproducibility of dispersions. By using a high pressure homogenizer and a three-rollcalendaring mill in combination, CNT reinforced epoxies were fabricated by mould castingwith a well dispersed nanofiller content from 0.1 to 2 wt%. The influence of the nano-carbonreinforcements on toughness and electrical properties of the CNT/epoxies was studied. Asubstantial increase of all mechanical properties already appeared at the lowest CNT content of0.1 wt%, but further raising the nanofiller concentration only led to moderate further changes.The most significant enhancement was obtained for fracture toughness, reaching up to 82%.The low percolation thresholds were confirmed by electrical conductivity measurements on thesame composites yielding a threshold value of only about 0.01 wt%. As corroborated by athorough microscopic analysis of the composites, mechanical and electrical enhancement pointsto the formation of an interconnected network of agglomerated CNTs.

    Emneord
    CNT, Epoxy
    HSV kategori
    Forskningsprogram
    Materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-169989 (URN)10.1088/0957-4484/22/12/125702 (DOI)
    Tilgjengelig fra: 2012-03-13 Laget: 2012-03-07 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    2. Comparing carbon nanotubes and graphene nanoplatelets as reinforcements in polyamide 12 composites
    Åpne denne publikasjonen i ny fane eller vindu >>Comparing carbon nanotubes and graphene nanoplatelets as reinforcements in polyamide 12 composites
    2011 (engelsk)Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 22, nr 27, s. 275714-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We investigate the influence of nanofillers including carbon nanotubes (CNTs) and graphene nanoplatelets on a thermoplastic engineering polymer, polyamide 12 (PA12). The comparison between these two important nanofillers as to how they influence the structure and properties of the polymer is systematically studied. The polymer–nanofiller composites were prepared using a twin-screw micro-extruder and the composite was thereafter hot pressed into thin films. The structure (using wide angle x-ray diffraction and differential scanning calorimetry) and properties (through tensile testing and conductivity measurement) of the thin films have been investigated. The composites incorporating surfactant showed the best CNT distribution and dispersion, causing an improvement of up to 80% in the toughness modulus over pure PA12. Electrical percolation could also be achieved at nanofiller concentrations of 1 to 2 wt%. In this study we observed that CNT fillers bring about more pronounced improvements in PA12 compared to graphene nanoplatelets, as far as mechanical and electrical properties are concerned.

    Emneord
    CNT, Polymer composite, Graphene
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-168031 (URN)10.1088/0957-4484/22/27/275714 (DOI)
    Tilgjengelig fra: 2012-02-06 Laget: 2012-02-03 Sist oppdatert: 2017-12-08bibliografisk kontrollert
    3. Investigation of crystalline and tensile properties of carbon nanotube-filled polyamide-12 fibers melt-spun by industry-related processes
    Åpne denne publikasjonen i ny fane eller vindu >>Investigation of crystalline and tensile properties of carbon nanotube-filled polyamide-12 fibers melt-spun by industry-related processes
    2012 (engelsk)Inngår i: Journal of Engineered Fibers and Fabrics, ISSN 1558-9250, E-ISSN 1558-9250, Vol. 7, nr 3Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The paper addresses the influence of carbon nanotubes (CNT) on the structure and mechanical properties of high tensile strength thermoplasticpolymer fibers. Polyamide (PA) fibers with different draw ratios, with and without CNTs as fillers, and having mechanical properties close to industrial standards were spun in a pilot melt spinning plant. The morphology of the fibers was investigated using optical microscopy, nuclear magnetic resonance (NMR) and 2-D wide angle x-ray diffraction (WAXD). Differential scanning calorimetry (DSC) was carried out to get an estimation of the crystallinity. For a concise interpretation of the results of tensile measurements performed on the fibers, a parameter was developed to account for the detrimental influence of polymer extrusion on their mechanical properties. CNTs seem to act as sites for the growth of un-oriented crystalline domains converted from oriented regions, without yielding a mechanical reinforcing effect.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-169990 (URN)
    Tilgjengelig fra: 2012-03-13 Laget: 2012-03-07 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    4. Mechanical reinforcement and thermal conductivity in expanded graphene nanoplatelets reinforced epoxy composites
    Åpne denne publikasjonen i ny fane eller vindu >>Mechanical reinforcement and thermal conductivity in expanded graphene nanoplatelets reinforced epoxy composites
    Vise andre…
    2012 (engelsk)Inngår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 531, s. 6-10Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Influence of reinforcements on mechanical and thermal properties of graphene nanoplatelets/epoxy com-posites is investigated. Amine functionalized expanded graphene nanoplatelets (EGNPs) were dispersed within epoxy resins using high-pressure processor followed by three roll milling. Functionality on the EGNPs was confirmed with FTIR and micro-Raman spectroscopy. Bending and nano-mechanical testingwas performed on the composites. Incorporation of EGNPs improved the flexural modulus and hardness of the composite and increased fracture toughness by up to 60%. Marked improvement was observed inthermal conductivity of the composites reaching 36% at 2 wt.% loading. Functionalized EGNPs exhibited significant improvements indicating favorable interaction at EGNPs/polymer interface.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-169994 (URN)10.1016/j.cplett.2012.02.006 (DOI)
    Tilgjengelig fra: 2012-03-13 Laget: 2012-03-07 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    5. The size and synergy effects of graphene nanoplatelets andcarbon nanotubes in mechanical properties of epoxy composites.
    Åpne denne publikasjonen i ny fane eller vindu >>The size and synergy effects of graphene nanoplatelets andcarbon nanotubes in mechanical properties of epoxy composites.
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    We study mechanical reinforcement in a widely used epoxy matrix with the addition of graphenenanoplatelets (GnPs) and various mixture ratios of carbon nanotubes (CNTs) withGnPs. Two different dimensions of GnPs were used with flake sizes of 5 mm and 25 mm toinvestigate the influence of nanofiller size on the composite properties. In the GnP reinforcedcomposites, the bigger flakes showed greater reinforcement at all GnP concentrations. The influenceof size on properties is significant as bigger flakes actively control the failure mechanismsin the composite. In the mixture samples, highest CNT content (9:1) showed significantimprovement in fracture toughness of 76 %. For composites with mixtures of CNTs andGnPs, the CNT:GnP ratio is an interesting factor significantly influencing the properties ofthe epoxy matrix. The combination of high aspect ratio of CNTs and larger surface area ofGnPs contribute to the synergistic effect of the CNT-GnP hybrid samples. Thermal conductivityconsistently increases with the incorporation of GnPs in the matrix. Transmission electronmicroscopy (TEM) images confirm the uniform nanofiller dispersion achieved in thecomposites with GnP. For the hybrid samples the CNTs are seen to align themselves on theGnP flakes creating an inter-connected strong nanofiller network in the matrix. The homogenousnanofiller dispersions have been achieved by high shear calendaring which is a methodcapable of being industrially scaled up.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-171572 (URN)
    Tilgjengelig fra: 2012-03-22 Laget: 2012-03-21 Sist oppdatert: 2012-04-13bibliografisk kontrollert
  • 9.
    Chatterjee, Sanjukta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    The size and synergy effects of graphene nanoplatelets andcarbon nanotubes in mechanical properties of epoxy composites.Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    We study mechanical reinforcement in a widely used epoxy matrix with the addition of graphenenanoplatelets (GnPs) and various mixture ratios of carbon nanotubes (CNTs) withGnPs. Two different dimensions of GnPs were used with flake sizes of 5 mm and 25 mm toinvestigate the influence of nanofiller size on the composite properties. In the GnP reinforcedcomposites, the bigger flakes showed greater reinforcement at all GnP concentrations. The influenceof size on properties is significant as bigger flakes actively control the failure mechanismsin the composite. In the mixture samples, highest CNT content (9:1) showed significantimprovement in fracture toughness of 76 %. For composites with mixtures of CNTs andGnPs, the CNT:GnP ratio is an interesting factor significantly influencing the properties ofthe epoxy matrix. The combination of high aspect ratio of CNTs and larger surface area ofGnPs contribute to the synergistic effect of the CNT-GnP hybrid samples. Thermal conductivityconsistently increases with the incorporation of GnPs in the matrix. Transmission electronmicroscopy (TEM) images confirm the uniform nanofiller dispersion achieved in thecomposites with GnP. For the hybrid samples the CNTs are seen to align themselves on theGnP flakes creating an inter-connected strong nanofiller network in the matrix. The homogenousnanofiller dispersions have been achieved by high shear calendaring which is a methodcapable of being industrially scaled up.

  • 10. Chatterjee, Sanjukta
    et al.
    Reifler, F A
    Chu, B T T
    Hufenus, R
    Investigation of crystalline and tensile properties of carbon nanotube-filled polyamide-12 fibers melt-spun by industry-related processes2012Inngår i: Journal of Engineered Fibers and Fabrics, ISSN 1558-9250, E-ISSN 1558-9250, Vol. 7, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper addresses the influence of carbon nanotubes (CNT) on the structure and mechanical properties of high tensile strength thermoplasticpolymer fibers. Polyamide (PA) fibers with different draw ratios, with and without CNTs as fillers, and having mechanical properties close to industrial standards were spun in a pilot melt spinning plant. The morphology of the fibers was investigated using optical microscopy, nuclear magnetic resonance (NMR) and 2-D wide angle x-ray diffraction (WAXD). Differential scanning calorimetry (DSC) was carried out to get an estimation of the crystallinity. For a concise interpretation of the results of tensile measurements performed on the fibers, a parameter was developed to account for the detrimental influence of polymer extrusion on their mechanical properties. CNTs seem to act as sites for the growth of un-oriented crystalline domains converted from oriented regions, without yielding a mechanical reinforcing effect.

  • 11. Chatterjee, Sanjukta
    et al.
    Wang, J W
    Kuo, W S
    Tai, N H
    Salzmann, C
    Li, W L
    Hollertz, R
    Nüesch, F A
    Chu, B T T
    Mechanical reinforcement and thermal conductivity in expanded graphene nanoplatelets reinforced epoxy composites2012Inngår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 531, s. 6-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Influence of reinforcements on mechanical and thermal properties of graphene nanoplatelets/epoxy com-posites is investigated. Amine functionalized expanded graphene nanoplatelets (EGNPs) were dispersed within epoxy resins using high-pressure processor followed by three roll milling. Functionality on the EGNPs was confirmed with FTIR and micro-Raman spectroscopy. Bending and nano-mechanical testingwas performed on the composites. Incorporation of EGNPs improved the flexural modulus and hardness of the composite and increased fracture toughness by up to 60%. Marked improvement was observed inthermal conductivity of the composites reaching 36% at 2 wt.% loading. Functionalized EGNPs exhibited significant improvements indicating favorable interaction at EGNPs/polymer interface.

  • 12.
    Espadas Escalante, Juan José
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik. Uppsala University.
    On numerical analyses of woven composite laminates: Homogenization, damage and fracture2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This dissertation analyzes various mechanical properties of textile reinforced composite laminates.

    The dissertation is based on a total of six published works, which are essentially numerical, although experimental elements are available. The numerical methods used are based on high-resolution finite element models in combination with sophisticated phase-field theories for brittle fracture. A key result is that important mechanical properties in engineering applications, such as fracture or damage resistance, can be substantially affected by the arrangement of the constituent materials at the meso level.

    Delarbeid
    1. A phase-field model for strength and fracture analyses of fiber-reinforced composites
    Åpne denne publikasjonen i ny fane eller vindu >>A phase-field model for strength and fracture analyses of fiber-reinforced composites
    2019 (engelsk)Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 174, s. 58-67Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A phase-field model for brittle fracture is proposed and evaluated for strength and fracture analyses of composites. In addition to the elastic properties, this approach makes use of only the fracture toughness and the strength of the material. The capability of the method is shown in analyses of composites at two scales. In laminates, strengths of notched laminates are estimated, including hole size effects. In a lamina, cracks developed in both transverse tension and compression are analyzed and compared to other numerical methods in the literature. The effects of a spectral and a hydrostatic-deviatoric decomposition of the strain energy density, two variants often used in phase-field formulations, are studied. It is shown that the choice of the decomposition affects the fracture development. Results are compared to experiments and simulations in the literature showing the capabilities of the phase-field approach.

    sted, utgiver, år, opplag, sider
    Elsevier, 2019
    Emneord
    Computational mechanics, Strength, Fracture, Finite element analysis (FEA)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-368254 (URN)10.1016/j.compscitech.2018.10.031 (DOI)000469407500008 ()
    Tilgjengelig fra: 2018-12-03 Laget: 2018-12-03 Sist oppdatert: 2019-07-05bibliografisk kontrollert
    2. A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites
    Åpne denne publikasjonen i ny fane eller vindu >>A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites
    2017 (engelsk)Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 160, s. 529-537Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The influence of boundary conditions (BCs) in the estimation of elastic properties of periodic structures is investigated using computational homogenization with special focus on planar structures. Uniform displacement, uniform traction, periodic, in-plane periodic and a proposed mix of periodic and traction BCs are used. First, the effect of the BCs is demonstrated in structures with one-, two- and three-dimensional periodicity. Mixed BCs are shown to most accurately represent the behavior of layered structures with a small number of repeating unit cells. Then, BCs are imposed on a twill woven composite architecture. Special attention is devoted to investigate the sensitivity of the estimated properties with respect to the BCs and to show differences when considering a single lamina or a laminate. High sensitivity of the in-plane extensional modulus and Poisson's ratio with respect to the type of BCs is found. Moreover, it is shown that the mix of BCs and in-plane periodic BCs are capable to represent an experimental strain field.

    Emneord
    Computational homogenization, Mixed boundary conditions, Heterogeneous structures, Elastic properties, Woven composites, Finite element method
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-359307 (URN)10.1016/j.compstruct.2016.10.082 (DOI)000390470300044 ()
    Tilgjengelig fra: 2018-08-31 Laget: 2018-08-31 Sist oppdatert: 2019-07-05bibliografisk kontrollert
    3. The effect of free-edges and layer shifting on intralaminar and interlaminar stresses in woven composites
    Åpne denne publikasjonen i ny fane eller vindu >>The effect of free-edges and layer shifting on intralaminar and interlaminar stresses in woven composites
    2018 (engelsk)Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 185, s. 212-220Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The free-edge effects and relative layer shifting in the interlaminar and intralaminar stresses of plain woven composite laminates under uniaxial extension is investigated numerically using a finite element approach. A computational framework of the free-edge problem for periodic structures with finite width is applied to woven laminates. First, two-layered laminates with three different shifting configurations are studied considering repeating unit cells simulating finite and infinite width. For each configuration, two different widths are considered by trimming the model at different locations in order to investigate different free-edge effects. Then, two four-layered laminates with no shifting and a maximum shifting configuration are analyzed to illustrate the effect of neighboring layers in the stresses. For each shifting configuration, different delamination mechanisms are expected. When considering more layers, it is found that the stacking configuration affects the state of stress and the free-edge effects depending on the shifting. In general, a different behavior than that of unidirectional tape laminates is found, since the interlaminar and intralaminar stresses can be higher than those generated at the free-edges. Particularly, for the maximum shifting configuration results are in agreement with experimental results in the literature where no debonding between yarns was observed at the free-edges.

    Emneord
    Woven composites, Finite element method, Intralaminar stresses, Interlaminar stresses, Free-edge effects, Multiscale modeling
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-341485 (URN)10.1016/j.compstruct.2017.11.014 (DOI)000418961000018 ()
    Tilgjengelig fra: 2018-02-28 Laget: 2018-02-28 Sist oppdatert: 2019-07-05bibliografisk kontrollert
    4. A study of induced delamination and failure in woven composite laminates subject to short-beam shear testing
    Åpne denne publikasjonen i ny fane eller vindu >>A study of induced delamination and failure in woven composite laminates subject to short-beam shear testing
    2019 (engelsk)Inngår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 205, s. 359-369Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Failure in woven composite laminates subject to global shear load is studied. Laminates are manufactured, tested and analyzed using X-ray computed tomography, scanning electron microscopy and finite element models. It is found that the stress distribution along the thickness direction is dependent on the layer shifting that alters different yarn interactions, which in turn, affects delamination and failure onset A suggested failure mechanism is in agreement with experimental observations.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-368250 (URN)10.1016/j.engfracmech.2018.10.015 (DOI)000453766000026 ()
    Tilgjengelig fra: 2018-12-03 Laget: 2018-12-03 Sist oppdatert: 2019-07-05bibliografisk kontrollert
    5. Analysis of the Influence of Layer Shifting on the Elastic Response and Damage Nucleation and Growth in Woven Composite Laminates
    Åpne denne publikasjonen i ny fane eller vindu >>Analysis of the Influence of Layer Shifting on the Elastic Response and Damage Nucleation and Growth in Woven Composite Laminates
    2018 (engelsk)Inngår i: NASA Technical MemorandumsArtikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-368253 (URN)
    Tilgjengelig fra: 2018-12-03 Laget: 2018-12-03 Sist oppdatert: 2019-07-05
    6. Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory
    Åpne denne publikasjonen i ny fane eller vindu >>Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory
    2019 (engelsk)Inngår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 216, artikkel-id 106523Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A phase-field approach to fracture is used to simulate transverse cracking kinetics in composite laminates. First, a typical unidirectional tape laminate is modeled and the transverse cracking evolution with the consequent reduction in the in-plane modulus of elasticity is estimated. Then, a four-layered plain weave composite is modeled using different layer shifting configurations. Predictions in the transverse cracking evolution become improved as the shifting configuration of the laminate model become closer to experimental observations. Simulations predict that some cracks do not form perpendicularly to the loading direction, as it has been observed experimentally in similar locations. Only the fracture toughness and the in situ transverse strength of the ply are required without prior knowledge of the position of the cracks or an ad hoc criterion for crack evolution. All the simulations are compared qualitatively and quantitatively to experiments published elsewhere.

    Emneord
    Composites, Fibre reinforced materials, Fracture mechanics, Damage mechanics, Crack growth
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot tillämpad mekanik
    Identifikatorer
    urn:nbn:se:uu:diva-388533 (URN)10.1016/j.engfracmech.2019.106523 (DOI)000477573000028 ()
    Tilgjengelig fra: 2019-07-01 Laget: 2019-07-01 Sist oppdatert: 2019-09-20bibliografisk kontrollert
  • 13.
    Espadas-Escalante, Juan José
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Bednarcyk, Brett A.
    NASA, Glenn Res Ctr, Cleveland, OH 44135 USA.
    Pineda, Evan J.
    NASA, Glenn Res Ctr, Cleveland, OH 44135 USA.
    Isaksson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Modeling the influence of layer shifting on the properties and nonlinear response of woven composites subject to continuum damage2019Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 220, s. 539-549Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of relative layer shifting on the elastic and damage response of plain weave composite laminates is analyzed using a continuum damage mechanics approach in combination with the finite element method. First, the homogenized properties of the woven composite as a function of the number of layers and of layer shifting are presented. Next, the damage development in various shifting configurations is studied using different damage constitutive models for the matrix and the fiber bundles. It is shown that the impact of layer shifting on both the elastic response and the nonlinear damage response is significant. Most notably, the model captures changes in the damage mechanisms within the woven composite that occur due to layer shifting, resulting in stiffer, more brittle behavior, which has been shown experimentally in the literature. Model results in the linear and nonlinear regimes are shown to be consistent with both an independent analytical model and reported experiments.

  • 14.
    Espadas-Escalante, Juan José
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    van Dijk, Nico P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Isaksson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    A phase-field model for strength and fracture analyses of fiber-reinforced composites2019Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 174, s. 58-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A phase-field model for brittle fracture is proposed and evaluated for strength and fracture analyses of composites. In addition to the elastic properties, this approach makes use of only the fracture toughness and the strength of the material. The capability of the method is shown in analyses of composites at two scales. In laminates, strengths of notched laminates are estimated, including hole size effects. In a lamina, cracks developed in both transverse tension and compression are analyzed and compared to other numerical methods in the literature. The effects of a spectral and a hydrostatic-deviatoric decomposition of the strain energy density, two variants often used in phase-field formulations, are studied. It is shown that the choice of the decomposition affects the fracture development. Results are compared to experiments and simulations in the literature showing the capabilities of the phase-field approach.

  • 15.
    Espadas-Escalante, Juan José
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    van Dijk, Nico P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Isaksson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites2017Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 160, s. 529-537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of boundary conditions (BCs) in the estimation of elastic properties of periodic structures is investigated using computational homogenization with special focus on planar structures. Uniform displacement, uniform traction, periodic, in-plane periodic and a proposed mix of periodic and traction BCs are used. First, the effect of the BCs is demonstrated in structures with one-, two- and three-dimensional periodicity. Mixed BCs are shown to most accurately represent the behavior of layered structures with a small number of repeating unit cells. Then, BCs are imposed on a twill woven composite architecture. Special attention is devoted to investigate the sensitivity of the estimated properties with respect to the BCs and to show differences when considering a single lamina or a laminate. High sensitivity of the in-plane extensional modulus and Poisson's ratio with respect to the type of BCs is found. Moreover, it is shown that the mix of BCs and in-plane periodic BCs are capable to represent an experimental strain field.

  • 16. Hollertz, R
    et al.
    Chatterjee, Sanjukta
    Guttmann, H
    Geiger, T
    Nüesch, F A
    Chu, B T T
    Improvement of toughness and electrical properties of epoxy composites with carbon nanotubes prepared by industrially relevant processes2011Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 22, nr 12, s. 125702-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The addition of carbon nanotubes (CNTs) to polymeric matrices or master batches has thepotential to provide composites with novel properties. However, composites with a uniformdispersion of CNTs have proved to be difficult to manufacture, especially at an industrial scale.This paper reports on processing methods that overcome problems related to the control andreproducibility of dispersions. By using a high pressure homogenizer and a three-rollcalendaring mill in combination, CNT reinforced epoxies were fabricated by mould castingwith a well dispersed nanofiller content from 0.1 to 2 wt%. The influence of the nano-carbonreinforcements on toughness and electrical properties of the CNT/epoxies was studied. Asubstantial increase of all mechanical properties already appeared at the lowest CNT content of0.1 wt%, but further raising the nanofiller concentration only led to moderate further changes.The most significant enhancement was obtained for fracture toughness, reaching up to 82%.The low percolation thresholds were confirmed by electrical conductivity measurements on thesame composites yielding a threshold value of only about 0.01 wt%. As corroborated by athorough microscopic analysis of the composites, mechanical and electrical enhancement pointsto the formation of an interconnected network of agglomerated CNTs.

  • 17.
    Holmgren, Jonna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kassman Rudolphi, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Friction and wear studies of some PEEK materials2014Inngår i: 16th Nordic Symposium on Tribology (NORDTRIB), 2014Konferansepaper (Annet vitenskapelig)
  • 18.
    Holmgren Lind, Jonna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kassman Rudolphi, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Effect of PTFE on the tribological behaviour of PPS with glass fiber2014Inngår i: 1st International conference on polymer tribology (PolyTrib), 2014Konferansepaper (Annet vitenskapelig)
  • 19.
    Huc, Sabina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik. Univ Boras, Fac Text Engn & Business, S-50190 Boras, Sweden.
    Hozjan, Tomaz
    Univ Ljubljana, Fac Civil & Geodet Engn, Ljubljana 1000, Slovenia.
    Svensson, Staffan
    Univ Boras, Fac Text Engn & Business, S-50190 Boras, Sweden.
    Rheological behavior of wood in stress relaxation under compression2018Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, nr 3, s. 793-808Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rheological behavior of wood under uniaxial compression along and perpendicular to the grain in constant environment was examined. Tests with constant deformation rate until failure and stress relaxation tests with constant deformation applied stepwise were carried out. The experimental results of stress relaxation showed nonlinear material behavior over time that got more prominent under high deformation levels. Considerable amount of stress relaxed during applying the deformation. Wood experienced greater stress relaxation along the grain than perpendicular to it. Three rheological models for orthotropic material were calibrated to the experimentally determined stress-time curves in longitudinal and transverse directions simultaneously. Small deformation levels assuming linear strains were accounted for in the models. Required elastic material parameters were determined from the tests with constant deformation rate. A model including the highest number of viscoelastic material parameters was the most successful in predicting stress relaxation of wood under stepwise deformation. Modeling indicated that wood behavior was very close to linear viscoelastic in relaxation under small deformation. The obtained material parameters made the model suitable for predicting rheological behavior of wood comprehensively, under sustained deformation or load in constant conditions.

  • 20.
    Huc, Sabina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik. Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Svensson, Staffan
    Univ Boras, Fac Text Engn & Business, SE-50190 Boras, Sweden.
    Influence of grain direction on the time-dependent behavior of wood analyzed by a 3D rheological model: A mathematical consideration2018Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 10, s. 889-897Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A three-dimensional (3D) rheological model for an orthotropic material subjected to sustained load or deformation under constant climate has been mathematically formulated. The elastic and viscoelastic compliance matrices are symmetric, where the mathematical derivation of the latter is shown. The model is linear and requires constant numerical values for the elastic and viscoelastic material parameters. The model's ability to predict the natural time-dependent response in three material directions simultaneously is demonstrated on a Douglas fir (Pseudotsuga menziesii) specimen subjected to a constant uniaxial tensile load. The material extends in a longitudinal direction and contracts in the transverse directions with time. The required material parameters are taken from the literature when possible, otherwise they are assumed. Furthermore, the influence of misalignment between the directions of observation and wood material directions on induced time-dependent strains is analyzed. The analyses show that the misalignment has a large effect on the material behavior. In some cases, the specimen under constant uniaxial tension even extends in the perpendicular transverse direction with time. The obtained results clearly demonstrate the high importance of considering the alignment of material directions precisely in order to be able to interpret the time-dependent behavior of wood correctly.

  • 21.
    Hägglund, Carl
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Department of Applied Physics, Chalmers University of Technology.
    Apell, Peter S.
    Department of Applied Physics, Chalmers University of Technology.
    Kasemo, Bengt
    Department of Applied Physics, Chalmers University of Technology.
    Maximized optical absorption in ultrathin films and its application to plasmon-based two-dimensional photovoltaics2010Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 10, nr 8, s. 3135-3141Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Hägglund, Carl
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Chalmers University of Technology.
    Apell, S. P.
    Chalmers University of Technology.
    Resource efficient plasmon-based 2D-photovoltaics with reflective support2010Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, nr S3, s. A343-A356Artikkel i tidsskrift (Fagfellevurdert)
  • 23.
    Isaksson, Per
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Carlsson, L. A.
    Florida Atlantic Univ, Dept Mech Engn, Boca Raton, FL 33431 USA..
    Analysis of the out-of-plane compression and shear response of paper-based web-core sandwiches subject to large deformation2017Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 159, s. 96-109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanical response of three different structural core sandwich panels in out-of-plane compression and shear has been analyzed. Specific core shapes examined are arc-tangent, wavy trapezoidal and hemispherical. Unit cells consisting of representative elements of the core attached to face sheets were selected for analysis. Both face sheets and core were assumed made from paper. Finite element analysis employing large deformation and rotations and orthotropic elastic-plastic behavior was used. The results show that the arc-tangent and trapezoidal cores are prone to collapse by extensive bending and buckling, whereas the hemispherical core behaved more stably in compression and shear. Core sheets with a hemispherical shape were prepared from copy paper sheets in a specially designed forming machine. Sandwich test specimens were prepared from this core and tested in out-of-plane compression, and the load-displacement response was compared to predictions from finite element simulations. The experimental and finite element results were consistent.

  • 24.
    Jansson, Jessica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Termoelaster i kompositkrut: En möjlig ersättning till nitrocellulosa2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Sedan människor började använda energetiska material har risken för oönskade explosioner alltid varit ett problem. Många produktionsanläggningar och förråd har förstörts på grund av oönskad antändning energetiska material. Idag är nitrocellulosa en komponent i de flesta kanonkrut. En negativ egenskap hos nitrocellulosa är att den bryts ner över tid och eftersom det är en naturprodukt så kommer det alltid att finnas en viss skillnad mellan olika batcher. Genom att ersätta nitrocellulosa med en produkt som inte bryts ner men som fortfarande ger liknande övriga egenskaper kan kanonkrutssäkerheten öka. Termoelaster undersöktes då de är smältbara och tåliga. Smältpunkt och glastransitionstemperaturen bestämdes med differentiell svepkalorimetri, viskositeten mättes vid flera temperaturer med en reometer och mekaniska egenskaper utvärderades i en dragprovningsmaskin. De två mest lovande polymererna blandades sedan med hexamin som är ett inert material för att simulera ett kompositkrut. Agglomerering av hexamin undveks genom tillsats av små mängder pyrogen kiseldioxid. Fyllnadsgraden i systemet nådde 70 viktprocent hexamin i en polymer. Kompositmaterialen dragprovades och resultaten jämfördes med motsvarande data för två nitrocellulosabaserat krut. Kompositmaterialen hade lägre brottgräns än det ena nitrocellulosabaserade krutet men högre brottgräns än det andra nitrocellulosabaserade krutet. Kompositmaterialen hade högre E-modul än det nitrocellulosabaserade krutet men lägre brottöjning. Resultaten är lovande och visar att termoelasterna har stor potential att användas i kompositkrut. Med fortsatt undersökning och optimering av kompositmaterialen kan ett säkrare alternativ till nitrocellulosa skapas.

  • 25.
    Jeong, Seung Hee
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Soft Intelligence: Liquids Matter in Compliant Microsystems2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Soft matter, here, liquids and polymers, have adaptability to a surrounding geometry. They intrinsically have advantageous characteristics from a mechanical perspective, such as flowing and wetting on surrounding surfaces, giving compliant, conformal and deformable behavior. From the behavior of soft matter for heterogeneous surfaces, compliant structures can be engineered as embedded liquid microstructures or patterned liquid microsystems for emerging compliant microsystems.

    Recently, skin electronics and soft robotics have been initiated as potential applications that can provide soft interfaces and interactions for a human-machine interface. To meet the design parameters, developing soft material engineering aimed at tuning material properties and smart processing techniques proper to them are to be highly encouraged. As promising candidates, Ga-based liquid alloys and silicone-based elastomers have been widely applied to proof-of-concept compliant structures.

    In this thesis, the liquid alloy was employed as a soft and stretchable electrical and thermal conductor (resistor), interconnect and filler in an elastomer structure. Printing-based liquid alloy patterning techniques have been developed with a batch-type, parallel processing scheme. As a simple solution, tape transfer masking was combined with a liquid alloy spraying technique, which provides robust processability. Silicone elastomers could be tunable for multi-functional building blocks by liquid or liquid-like soft solid inclusions. The liquid alloy and a polymer additive were introduced to the silicone elastomer by a simple mixing process. Heterogeneous material microstructures in elastomer networks successfully changed mechanical, thermal and surface properties.

    To realize a compliant microsystem, these ideas have in practice been useful in designing and fabricating soft and stretchable systems. Many different designs of the microsystems have been fabricated with the developed techniques and materials, and successfully evaluated under dynamic conditions. The compliant microsystems work as basic components to build up a whole system with soft materials and a processing technology for our emerging society.

    Delarbeid
    1. Liquid alloy printing of microfluidic stretchable electronics
    Åpne denne publikasjonen i ny fane eller vindu >>Liquid alloy printing of microfluidic stretchable electronics
    Vise andre…
    2012 (engelsk)Inngår i: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 22, nr 12, s. 4657-4664Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Recently, microfluidic stretchable electronics has attracted great interest from academia since conductive liquids allow for larger cross-sections when stretched and hence low resistance at longer lengths. However, as a serial process it has suffered from low throughput, and a parallel processing technology is needed for more complex systems and production at low costs. In this work, we demonstrate such a technology to implement microfluidic electronics by stencil printing of a liquid alloy onto a semi-cured polydimethylsiloxane (PDMS) substrate, assembly of rigid active components, encapsulation by pouring uncured PDMS on-top and subsequent curing. The printing showed resolution of 200 mm and linear resistance increase of the liquid conductors when elongated up to 60%. No significant change of resistance was shown for a circuit with one LED after 1000 times of cycling between a 0% and an elongation of 60% every 2 s. A radio frequency identity (RFID) tag was demonstrated using the developed technology, showing that good performance could be maintained well into the radio frequency (RF) range.

    sted, utgiver, år, opplag, sider
    Royal society of chemistry, 2012
    Emneord
    liquid alloy, printing, stretchable electronics, wireless communication
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik; Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-183278 (URN)10.1039/C2LC40628D (DOI)000310865200010 ()
    Tilgjengelig fra: 2012-10-23 Laget: 2012-10-23 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    2. Adhesive transfer soft lithography: low-cost and flexible rapid prototyping of microfluidic devices, Micro and Nanosystems
    Åpne denne publikasjonen i ny fane eller vindu >>Adhesive transfer soft lithography: low-cost and flexible rapid prototyping of microfluidic devices, Micro and Nanosystems
    2014 (engelsk)Inngår i: micro and nanosystems, ISSN 1876-4037, Vol. 6, s. 42-49Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A simple and low-cost approach was proposed for prototyping PDMS based microfluidic devices by transferringadhesive film microstructures onto a flexible substrate as a mould for PDMS replicas. The microstructures were engravedon an adhesive coated film using a commercial cutting plotter and then transferred (or laminated) onto a flexiblesubstrate, allowing for engraved isolated patterns. The proposed technique was demonstrated by a hydrodynamic focusingmicrofluidic device, having splitting and re-combining sheath channels. The whole processing could be finished within 1h in a normal laboratory environment. This approach offers an easy, flexible and rapid prototyping of microfluidic andlab-on-a-chip devices to users without expertise in microfabrication. In addition, by minimizing the use of chemicals, theprocess becomes more environmentally friendly than conventional photolithography based micro-fabrication techniques.

    sted, utgiver, år, opplag, sider
    Bentham Science Publishers, 2014
    Emneord
    liquid alloy, printing, soft lithography, rapid prototyping
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-239241 (URN)
    Tilgjengelig fra: 2014-12-19 Laget: 2014-12-19 Sist oppdatert: 2016-04-22
    3. Tape Transfer Printing of a Liquid Metal Alloy for Stretchable RF Electronics
    Åpne denne publikasjonen i ny fane eller vindu >>Tape Transfer Printing of a Liquid Metal Alloy for Stretchable RF Electronics
    2014 (engelsk)Inngår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, nr 9, s. 16311-16321Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In order to make conductors with large cross sections for low impedance radio frequency (RF) electronics, while still retaining high stretchability, liquid-alloy-based microfluidic stretchable electronics offers stretchable electronic systems the unique opportunity to combine various sensors on our bodies or organs with high-quality wireless communication with the external world (devices/systems), without sacrificing enhanced user comfort. This microfluidic approach, based on printed circuit board technology, allows large area processing of large cross section conductors and robust contacts, which can handle a lot of stretching between the embedded rigid active components and the surrounding system. Although it provides such benefits, further development is needed to realize its potential as a high throughput, cost-effective process technology. In this paper, tape transfer printing is proposed to supply a rapid prototyping batch process at low cost, albeit at a low resolution of 150 mu m. In particular, isolated patterns can be obtained in a simple one-step process. Finally, a stretchable radio frequency identification (RFID) tag is demonstrated. The measured results show the robustness of the hybrid integrated system when the tag is stretched at 50% for 3000 cycles.

    Emneord
    tape transfer printing, liquid metal alloy, microfluidic stretchable electronics, stretchable RF electronics, radio frequency identification (RFID) tag
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-237588 (URN)10.3390/s140916311 (DOI)000343106600041 ()
    Tilgjengelig fra: 2014-12-05 Laget: 2014-12-03 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    4. Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer
    Åpne denne publikasjonen i ny fane eller vindu >>Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer
    2015 (engelsk)Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, s. 8419-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Stretchable electronics offers unsurpassed mechanical compliance on complex or soft surfaces like the human skin and organs. To fully exploit this great advantage, an autonomous system with a self-powered energy source has been sought for. Here, we present a new technology to pattern liquid alloys on soft substrates, targeting at fabrication of a hybrid-integrated power source in microfluidic stretchable electronics. By atomized spraying of a liquid alloy onto a soft surface with a tape transferred adhesive mask, a universal fabrication process is provided for high quality patterns of liquid conductors in a meter scale. With the developed multilayer fabrication technique, a microfluidic stretchable wireless power transfer device with an integrated LED was demonstrated, which could survive cycling between 0% and 25% strain over 1,000 times.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-247504 (URN)10.1038/srep08419 (DOI)000349245600018 ()25673261 (PubMedID)
    Tilgjengelig fra: 2015-03-19 Laget: 2015-03-19 Sist oppdatert: 2017-12-04bibliografisk kontrollert
    5. Stretchable wireless power transfer with a liquid alloy coil
    Åpne denne publikasjonen i ny fane eller vindu >>Stretchable wireless power transfer with a liquid alloy coil
    2015 (engelsk)Inngår i: Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, 2015, s. 1137-1140Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    An integrated stretchable wireless power transfer device was demonstrated by packaging rigid electronic chips onto a liquid alloy coil patterned on a half-cured polydimethylsiloxane (PDMS) surface. To obtain low enough resistance, the long liquid alloy coil with a large cross section was made with a tape transfer masking followed by spray deposition of the liquid alloy. The measured results indicated the wireless power transfer efficiency reached 10% at 140 kHz and good performance under 25% overall strain. Different sizes of liquid alloy coils and a soft magnetic composite core were tested to improve the efficiency of the system.

    Serie
    Proceedings IEEE Micro Electro Mechanical Systems, ISSN 1084-6999
    Emneord
    Liquid alloy, Stretchable electronics, Wireless power transfer, Smart system integration
    HSV kategori
    Forskningsprogram
    Materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-265529 (URN)10.1109/MEMSYS.2015.7051165 (DOI)000370382900296 ()978-1-4799-7955-4 (ISBN)
    Konferanse
    Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, Estoril, January 18-22, 2015
    Tilgjengelig fra: 2015-10-31 Laget: 2015-10-31 Sist oppdatert: 2016-04-21bibliografisk kontrollert
    6. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
    Åpne denne publikasjonen i ny fane eller vindu >>Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
    Vise andre…
    2015 (engelsk)Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, artikkel-id 18257Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-272055 (URN)10.1038/srep18257 (DOI)000366451800001 ()26671673 (PubMedID)
    Forskningsfinansiär
    Swedish Research Council, 621-2010-5443 621-2014-5596Swedish Foundation for Strategic Research , EM11-0002 SE13-0061
    Tilgjengelig fra: 2016-01-12 Laget: 2016-01-11 Sist oppdatert: 2017-11-30bibliografisk kontrollert
    7. PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
    Åpne denne publikasjonen i ny fane eller vindu >>PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
    Vise andre…
    2016 (engelsk)Inngår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, nr 28, s. 5830-5836Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Targeting good user experiences, softness and stretchability are essential features for epidermal devices in body signal monitoring and body area stimulation. A highly soft, stretchable and sticky polydimethylsiloxane based elastomer (S3-PDMS) is achieved by a simple process with a widely used siloxane precursors, the properties of which are tuned by adding small fractions of an amine-based polymer, ethoxylated polyethylenimine (EPEI). This allows formation of a thick unobstrusive patch and may ease implementation of epidermal electronics in wearable healthcare applications. 

    Emneord
    Adhesion, Compliance, Elongation at break, Epidermal electronics, PDMS-based elastomer tuning
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-281212 (URN)10.1002/adma.201505372 (DOI)000382400900004 ()
    Forskningsfinansiär
    Swedish Research Council, 2010-5443
    Tilgjengelig fra: 2016-03-21 Laget: 2016-03-21 Sist oppdatert: 2017-11-30bibliografisk kontrollert
    8. Stretchable thermoelectric generators metallized with liquid alloy
    Åpne denne publikasjonen i ny fane eller vindu >>Stretchable thermoelectric generators metallized with liquid alloy
    Vise andre…
    2017 (engelsk)Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 18, s. 15791-15797Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Conventional thermoelectric generators (TEGs) are normally hard, rigid, and flat. However, most objects have curvy surfaces, which require soft and even stretchable TEGs for maximizing efficiency of thermal energy harvesting. Here, soft and stretchable TEGs using conventional rigid Bi2Te3 pellets metallized with a liquid alloy is reported. The fabrication is implemented by means of a tailored layer-by-layer fabrication process. The STEGs exhibit an output power density of 40.6 mu W/cm(2) at room temperature. The STEGs are operational after being mechanically stretched-and-released more than 1000 times, thanks to the compliant contact between the liquid alloy interconnects and the rigid pellets. The demonstrated interconnect scheme will provide a new route to the development of soft and stretchable energy-harvesting avenues for a variety of emerging electronic applications.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-281213 (URN)10.1021/acsami.7b04752 (DOI)000401307100064 ()28453282 (PubMedID)
    Forskningsfinansiär
    Swedish Foundation for Strategic Research , EM11-0002, SE13-0061Swedish Research Council, 621-2014-5596
    Tilgjengelig fra: 2016-03-21 Laget: 2016-03-21 Sist oppdatert: 2017-07-04bibliografisk kontrollert
  • 26.
    Jeong, Seung Hee
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Chen, Si
    Chalmers University of Technology.
    Huo, Jinxing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Gravier, Laurent
    University of Applied Sciences and Arts Western Switzerland.
    Gamstedt, Erik Kristofer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Liu, Johan
    Chalmers University of Technology.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Zhi-Bin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wu, Zhigang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Peoples R China.
    Hjort, Klas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thermal Elastomer Composites for Soft Transducers2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There is a need for thermal elastomer composites (TEC) which are stretchable, electrically insulating and easily processablefor soft and stretchable sensor or actuator systems as a thermal conductor or heat spreader at an interface or in a package.A novel TEC was made by embedding a gallium based liquid alloy (Galinstan) as a droplet in polydimethylsiloxane (PDMS,Elastosil RT 601) matrix with a high speed mechanical mixing process.

  • 27.
    Joffre, Thomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Miettinen, Arttu
    Wernersson, Erik L. G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Isaksson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Gamstedt, E. Kristofer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Effects of defects on the tensile strength of short-fibre composite materials2014Inngår i: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 75, s. 125-134Artikkel i tidsskrift (Fagfellevurdert)
  • 28.
    Joffre, Thomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wernersson, Erik L. G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Miettinen, Arttu
    Luengo Hendriks, Cris L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Gamstedt, E. Kristofer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Swelling of cellulose fibres in composite materials: Constraint effects of the surrounding matrix2013Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 74, s. 52-59Artikkel i tidsskrift (Fagfellevurdert)
  • 29.
    Källquist, Ida
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lithium titanium oxide materials for hybrid supercapacitor applications2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The objective of this thesis was to investigate the suitability of some different Li4Ti5O12 materials as a negative electrode in hybrid supercapacitors. A hybrid supercapacitor is a combination of a battery and an electric double-layer capacitor that uses both a battery material and a capacitor material in the same device. The target for these combination devices is to bridge the performance gap between batteries and capacitors and enable both high energy and power density. To achieve this, materials with high capacity as well as high rate capability are needed. To improve the rate of the commonly slow battery materials nanosizing has been found to be an effective solution.

    This study shows that Li4Ti5O12 has a significantly higher experimental capacity than the most common capacitor material, activated carbon. The capacity remained high even at high discharge rates due to a successful nanostructuring that increased the accessibility of the material and shortened the diffusion distance for the ions, leading to a much improved power performance compared with the bulk material. The use of a nanostructured Li4Ti5O12 material in a hybrid device together with activated carbon was estimated to double the energy density compared to an electric double-layer capacitor and maintain the same good power performance. To further increase the energy density also improved materials for the positive electrode should be investigated.

  • 30.
    Larsson, Niklas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Gradient formation in cemented carbides with 85Ni:15Fe-binder phase2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In today’s inserts used for metal cutting the binder phase consists of cobalt (Co).However, EU’s REACH programme and the U.S’s National Toxicity Programme(NTP) classified Co as toxic/carcinogenic. Therefore, there is a strong need toinvestigate alternative binder phases. This thesis covers sintering and characterisationof cemented carbide with a binder phase consisting of nickel (Ni) and iron (Fe) withthe composition of 85Ni:15Fe. The aim was to study the gradient formation of turninginsert and find sintering processes to achieve a gradient structure with the targetedthickness of 26 microns.

    Simulations in ThermoCalc provided a suitable composition and a starting point forsintering parameters. The influences of sintering process parameters, such as holdingtime, temperature and counter pressure on the formation of the gradient zone wereinvestigated. Hot isostatic pressing (HIP) sintering was done in order to study thegradient formation as well as to reduce the porosity when needed. Sintered insertswere analysed by light optical microscopy.

    It was found that there are at least three possible ways to control the formation ofthe gradient: sintering in vacuum with a holding time of 20 min at 1450°C, sintering at1450°C with a counter pressure of 5 mbar nitrogen, and sintering with a counterpressure of 11.5 mbar followed by a double sinter-hip with 55 bar argon atmosphere.However, only the last process fulfilled the microstructure criteria in terms ofporosity and binder phase distribution. It is clear that the formation of gradient zonesin 85Ni:15Fe can be predicted, however calculations and simulations need to beoptimized in order to get more accurate results.

  • 31. Lima, L.
    et al.
    Moreira, Milena
    Cioldin, F.
    Diniz, J. A.
    Doi, I.
    Tantalum Nitride as Promissing Gate Electrode for MOS Technology2010Inngår i: ECS Transactions, ISSN 1938-5862, E-ISSN 1938-6737, Vol. 31, nr 1, s. 319-325Artikkel i tidsskrift (Fagfellevurdert)
  • 32. Lima, L.
    et al.
    Moreira, Milena
    Diniz, J.
    Doi, I.
    Titanium nitride as promising gate electrode for MOS technology2012Inngår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, nr 6, s. 1427-1430Artikkel i tidsskrift (Fagfellevurdert)
  • 33.
    Lind, Jonna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kassman Rudolphi, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Cross section microscopy studies of wear tested polymer composites2016Konferansepaper (Annet vitenskapelig)
  • 34.
    Lind, Jonna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kassman Rudolphi, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Cross sections studies of polymer composites2016Konferansepaper (Annet vitenskapelig)
  • 35.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Calcium Phosphate Based Biomaterials for Bone Augmentation2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Basic (apatite-based) calcium phosphate cements (CPCs), and acidic (brushite and monetite-based) CPCs are used as bone replacement materials because of their bioactivity, mouldability and ability to harden in place. However, their application is limited by their inherent brittleness and difficulties related to their handling. The current thesis aimed to provide solutions to these limitations.

    To assess the baseline, the mechanical properties of two promising experimental and two commercially available apatite and brushite cements were investigated. The two experimental CPCs exhibited significantly higher mechanical strengths than the two commercially available ones, warranting further advancement of the former towards clinical use.

    The setting reaction of brushite cements was, for the first time, quantitatively studied in the first seconds and minutes, using synchrotron X-ray diffraction. The reaction was found to include a fast nucleation induction period (<9 s), nucleation (<18 s), brushite content increase and setting completion. The effect of the commonly used retardant citric acid – which usually also gives stronger brushite cements - was also evaluated, providing important information for further cement development.  

    To overcome complicated usage and short shelf life of acidic CPCs, a ready-to-use acidic CPC was developed by mixing a monocalcium phosphate monohydrate (MCPM) paste and a β-tricalcium phosphate (β-TCP) paste with suitable amounts of citric acid. The CPC showed adequate shelf life, good cohesion and mechanical performance.

    To mitigate against the brittle behavior of CPCs, i) poly(vinyl alcohol) fibres were used to reinforce apatite cements, significantly improving the apatite matrix’s toughness and resistance to cracking; ii) injectable, ready-to-use organic-inorganic composites with partly elastomeric compression behavior were designed based on silk fibroin hydrogels and acidic calcium phosphates, and their ability for antibiotic drug delivery was assessed. 

    In summary, insights into the functional properties of currently available CPCs as well as the setting process of brushite cements were gained and several new calcium phosphate-based formulations were developed to overcome some of the drawbacks of traditional CPCs. Further studies, in particular of the biological response, are needed to verify the potential of the developed materials for future use in the clinical setting. 

     

    Delarbeid
    1. Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
    Åpne denne publikasjonen i ny fane eller vindu >>Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
    Vise andre…
    2016 (engelsk)Inngår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 60, s. 617-627Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Calcium phosphate cements (CPCs) are widely used in bone repair. Currently there are two main types of CPCs, brushite and apatite. The aim of this project was to evaluate the mechanical properties of particularly promising experimental brushite and apatite formulations in comparison to commercially available brushite- and apatite-based cements (chronOS Inject and Norian® SRS®, respectively), and in particular evaluate the diametral tensile strength and biaxial flexural strength of these cements in both wet and dry conditions for the first time. The cements׳ porosity and their compressive, diametral tensile and biaxial flexural strength were tested in wet (or moist) and dry conditions. The surface morphology was characterized by scanning electron microscopy. Phase composition was assessed with X-ray diffraction. It was found that the novel experimental cements showed better mechanical properties than the commercially available cements, in all loading scenarios. The highest compressive strength (57.2±6.5 MPa before drying and 69.5±6.0 MPa after drying) was found for the experimental brushite cement. This cement also showed the highest wet diametral tensile strength (10.0±0.8 MPa) and wet biaxial flexural strength (30.7±1.8 MPa). It was also the cement that presented the lowest porosity (approx. 12%). The influence of water content was found to depend on cement type, with some cements showing higher mechanical properties after drying and some no difference after drying.

    Emneord
    Calcium phosphate cement; Brushite; Apatite; Compressive strength; Tensile strength; Flexural strength
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-284218 (URN)10.1016/j.jmbbm.2016.03.028 (DOI)000378969100055 ()27082025 (PubMedID)
    Forskningsfinansiär
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-2047Swedish Research Council, 621-2011-6258
    Tilgjengelig fra: 2016-04-15 Laget: 2016-04-15 Sist oppdatert: 2018-08-10bibliografisk kontrollert
    2. In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth
    Åpne denne publikasjonen i ny fane eller vindu >>In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth
    Vise andre…
    2017 (engelsk)Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 41, s. 36392-36399Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Brushite cements are fast self-setting materials that can be used as bone substitute materials. Although tracing their fast setting process is a challenge, it is important for the understanding of the same, which in turn is important for the material’s further development and use in the clinics. In this study, the setting rate, phase formation, and crystal growth of brushite cements were quantitatively studied by in situ synchrotron powder X-ray diffraction (SXRD) on a time scale of seconds. The influence of reactant ratios and a retardant (citric acid) on the setting reaction were analyzed. To complement the in situ investigations, scanning electron microscopy was carried out for ex situ morphological evolution of crystals. The initial reaction followed a four-step process, including a fast nucleation induction period, nucleation, crystal growth, and completion of the setting. The brushite crystal size grew up to the micro scale within 1 min, and the brushite content increased linearly after the nucleation until all monocalcium phosphate monohydrate (MCPM; Ca(H2PO4)2·H2O) had dissolved within minutes, followed by a slow increase until the end of the monitoring. By adjusting the MCPM to the β-tricalcium phosphate (β-TCP, β-Ca3(PO4)2) ratio in the starting powders, the brushite/monetite ratio in the cements could be modified. In the presence of citric acid, the formation of brushite nuclei was not significantly retarded, whereas the increase in brushite content and the growth of crystal size were effectively hindered. The amount of monetite also increased by adding citric acid. This is the first time that the brushite setting process has been characterized in the first seconds and minutes of the reaction by SXRD.

    Emneord
    synchrotron X-ray diffraction, setting reaction process, brushite cement, crystal size, citric acid, MCPM/β-TCP ratio
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-330146 (URN)10.1021/acsami.7b10159 (DOI)000413503700092 ()
    Tilgjengelig fra: 2017-09-26 Laget: 2017-09-26 Sist oppdatert: 2018-08-10bibliografisk kontrollert
    3. A ready-to-use acidic calcium phosphate cement
    Åpne denne publikasjonen i ny fane eller vindu >>A ready-to-use acidic calcium phosphate cement
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Premixed calcium phosphate cements have been developed to simplify the usage of traditional calcium phosphate cements and reduce the influence of the setting reaction on the delivery process. However, difficulties in achieving a good cohesion, adequate shelf life and sufficient mechanical properties have so far impeded their use in clinical applications, especially for the more degradable acidic calcium phosphate cements.

    In this study, a brushite cement was developed from a series of ready-to-use calcium phosphate pastes. The brushite cement paste was formed via mixing of a monocalcium phosphate monohydrate (MCPM) paste and a β-tricalcium phosphate (β-TCP) paste with good injectability and adequate shelf life. The MCPM paste was based on a water-immiscible liquid with two surfactants and the β-TCP paste on a sodium hylauronate aqueous solution. The effect of citric acid as a retardant was assessed. Formulations with suitable amounts of citric acid showed good cohesion and mechanical performance with potential for future clinical applications.

    Emneord
    Ready-to-use, acidic calcium phosphate cement, brushite, cohesion, injectability, shelf life
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-356978 (URN)
    Tilgjengelig fra: 2018-08-09 Laget: 2018-08-09 Sist oppdatert: 2018-08-10
    4. The addition of poly(vinyl alcohol) fibres to apatitic calcium phosphate cement can improve its toughness
    Åpne denne publikasjonen i ny fane eller vindu >>The addition of poly(vinyl alcohol) fibres to apatitic calcium phosphate cement can improve its toughness
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Calcium phosphate cements, and in particular hydroxyapatite cements, have been widely investigated for use as bone void fillers due to their chemical similarity to bone and related osteoconductivity. However, they are brittle, which limits their use to non-load-bearing applications.

    The aim of the current study was to improve the toughness of hydroxyapatite cements through fibre reinforcement. The effect of the addition of hydrophilic, poly(vinyl-alcohol) (PVA) fibres to hydroxyapatite cement was evaluated in terms of mechanical properties, including compressive strength, diametral tensile strength and toughness (work of fracture), as well as setting time, phase composition and cement morphology. The fibre reinforcement enhanced the fracture resistance of the hydroxyapatite cement, but also simultaneously reduced the compressive strength and setting time of the cements. However, cement with 5 wt% of fibres (of powder component) could be considered a good compromise, with a compressive strength of 46.5 ± 4.6 MPa (compared to 62.3 ± 12.8 MPa of that without fibres), i.e. still much greater than that of human trabecular bone (0.1-14 MPa). A significantly higher diametral tensile strength (9.2 ± 0.4 MPa) was found for this cement compared to that without fibres (7.4 ± 1.5 MPa). The work of fracture increased four times to 9.1 ± 1.5 kJ/m2 in comparison to the pristine apatite. In summary, the hydroxyapatite cements could be reinforced by suitable amounts of PVA fibres, which resulted in enhancing the material’s structural integrity and ductility, and increased the material’s resistance to cracking.

    Emneord
    fibre reinforcement, apatite cement, poly(vinyl alcohol), composite, compressive strength, work of fracture, diametral tensile strength, toughness
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-356979 (URN)
    Tilgjengelig fra: 2018-08-09 Laget: 2018-08-09 Sist oppdatert: 2018-08-10
    5. Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate – A simple way of producing injectable, bioactive and drug-loadable composites for biomedical applications
    Åpne denne publikasjonen i ny fane eller vindu >>Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate – A simple way of producing injectable, bioactive and drug-loadable composites for biomedical applications
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    silk fibroin, acidic calcium phosphates, composites, hydrogels, mechanical strength, drug-loadable
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-356991 (URN)
    Tilgjengelig fra: 2018-08-10 Laget: 2018-08-10 Sist oppdatert: 2018-08-10
  • 36.
    Luo, Jun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wu, Dan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate – A simple way of producing injectable, bioactive and drug-loadable composites for biomedical applicationsManuskript (preprint) (Annet vitenskapelig)
  • 37.
    Löwe, Rakel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Utvärdering av mekanisk provning av fiberförstärkt plast2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this work four fiber-reinforced polymers and one polymer were tested with four different mechanical testing methods, namely; vickers harness test, scratch test, fatigue test and tensile stress. The testing methods were evaluated according to their applicability on the materials mentioned. The purpose of the work is to give the reader an insight of what mechanical properties of materials mean and what kinds of properties one can expect from fiber-reinforced polymers. The purpose is also to give the reader a good sense of what can be expected from the methods tested on fiber-reinforced polymers. Vickers harness test was found to be a valid method as long as the surface of the material was neither uneven nor processed. Scratch test was found to be an overall good method but was recommended to be used in combination with scanning electron microscope, or other imaging tool for strong magnification. Processing of surfaces proved to affect the results. Tensile test was proved to give the user a good perception of the properties of the material, as long as the material not was woven. Woven materials found to differ a lot from each other. One conclusion from this result is that woven materials are best to be tested several times. Fatigue test was found to require more preparatory time and calculations to be able to give the user any useful results, the loads used in the project was found to be too light weight. Processed surfaces were found to be hard to examine in a scanning electron microscope.

  • 38.
    Marthin, Otte
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Gamstedt, E. Kristofer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Damage shielding mechanisms in hierarchical composites in nature with potential for design of tougher structural materials2019Inngår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, nr 3, artikkel-id 181733Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Load-carrying materials in nature, such as wood and bone, consist of relatively simple building blocks assembled into a hierarchical structure, ranging from the molecular scale up to the macroscopic level. This results in composites with a combination of high strength and high toughness, showing very large fracture surfaces indicating energy dissipation by cracking on multiple length scales. Man-made composites instead consist typically of fibres embedded in a uniform matrix, and frequently show brittle failure through the growth of critical clusters of broken fibres. In this paper, a hierarchical structure inspired by wood is presented. It is designed to incapacitate cluster growth, with the aim of retaining high strength. This is done by introducing new structural levels of successively weaker interfaces with the purpose of reducing the stress concentrations if large clusters appear. To test this hypothesis, a probability density field of further damage growth has been calculated for different microstructures and initial crack sizes. The results indicate that the hierarchical structure should maintain its strength by localization of damage, yet rendering large clusters less harmful by weakening the resulting stress concentration to its surroundings, which would lead to an increase in strain to failure. In this context, the potential of using the biomimetic hierarchical structure in design of composite materials is discussed.

  • 39. Moreira, Milena
    IR-reflectance assessment of the tilt angle of AlN-wurtzite films for shear mode resonators2013Konferansepaper (Fagfellevurdert)
  • 40. Moreira, Milena
    et al.
    Doi, I.
    Souza, J. F.
    Diniz, J. A.
    Electrical characterization and morphological properties of AlN films prepared by dc reactive magnetron sputtering2011Inngår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 88, nr 5, s. 802-806Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    Nygren, Kristian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Magnetron Sputtering of Nanocomposite Carbide Coatings for Electrical Contacts2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Today’s electronic society relies on the functionality of electrical contacts. To achieve good contact properties, surface coatings are normally applied. Such coatings should ideally fulfill a combination of different properties, like high electrical conductivity, high corrosion resistance, high wear resistance and low cost. A common coating strategy is to use noble metals since these do not form insulating surface oxides. However, such coatings are expensive, have poor wear resistance and they are often applied by electroplating, which poses environmental and human health hazards.

    In this thesis, nanocomposite carbide-based coatings were studied and the aim was to evaluate if they could exhibit properties that were suitable for electrical contacts. Coatings in the Cr-C, Cr-C-Ag and Nb-C systems were deposited by magnetron sputtering using research-based equipment as well as industrial-based equipment designed for high-volume production. To achieve the aim, the microstructure and composition of the coatings were characterized, whereas mechanical, tribological, electrical, electrochemical and optical properties were evaluated. A method to optically measure the amount of carbon was developed.

    In the Cr-C system, a variety of deposition conditions were explored and amorphous carbide/amorphous carbon (a-C) nanocomposite coatings could be obtained at substrate temperatures up to 500 °C. The amount of a-C was highly dependent on the total carbon content. By co-sputtering with Ag, coatings comprising an amorphous carbide/carbon matrix, with embedded Ag nanoclusters, were obtained. Large numbers of Ag nanoparticles were also found on the surfaces. In the Nb-C system, nanocrystalline carbide/a-C coatings could be deposited. It was found that the nanocomposite coatings formed very thin passive films, consisting of both oxide and a-C.

    The Cr-C coatings exhibited low hardness and low-friction properties. In electrochemical experiments, the Cr-C coatings exhibited high oxidation resistance. For the Cr-C-Ag coatings, the Ag nanoparticles oxidized at much lower potentials than bulk Ag. Overall, electrical contact resistances for optimized samples were close to noble metal references at low contact load. Thus, the studied coatings were found to have properties that make them suitable for electrical contact applications.

    Delarbeid
    1. Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Cr-C films
    Åpne denne publikasjonen i ny fane eller vindu >>Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Cr-C films
    Vise andre…
    2014 (engelsk)Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 305, s. 143-153Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Cr C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Cr C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 degrees C were X-ray amorphous and 500 C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl(sat. KG) in hot 1 mM H-2 SO4 resulted in oxidation of Cr C, yielding Cr203 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Cr C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes. (C) 2014 Elsevier B.V. All rights reserved.

    Emneord
    Chromium carbide, Magnetron sputtering, Nanocomposite, Deposition temperature, Carbon oxidation
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-227992 (URN)10.1016/j.apsusc.2014.03.014 (DOI)000336525400020 ()
    Tilgjengelig fra: 2014-07-04 Laget: 2014-07-02 Sist oppdatert: 2017-12-30
    2. Growth and characterization of chromium carbide films deposited by high rate reactive magnetron sputtering for electrical contact applications
    Åpne denne publikasjonen i ny fane eller vindu >>Growth and characterization of chromium carbide films deposited by high rate reactive magnetron sputtering for electrical contact applications
    Vise andre…
    2014 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 260, s. 326-334Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Chromium carbide films with different phase contents were deposited at 126±26 °C by industrial high rate reactivemagnetron sputtering, using both direct current magnetron sputtering (DCMS) and high power impulsemagnetron sputtering (HiPIMS). Film structure and properties were studied by SEM, XRD, TEM, XPS, NRA, Raman spectroscopy, nanoindentation, unlubricated reciprocating sliding experiments, and a laboratory setup to measure electrical contact resistance. The films consisted of amorphous a-CrCy, a nanocrystalline minority phase of metastable cubic nc-CrCx, and a hydrogenated graphite-like amorphous carbon matrix (a-C:H). The DCMS and HiPIMS processes yielded films with similar phase contents and microstructures, as well as similar functional properties. Low elastic modulus, down to 66 GPa, indicated good wear properties via a hardness/elastic modulus (H/E) ratio of 0.087. Unlubricated steady-state friction coefficients down to 0.13 were obtained for films with 69 at.% carbon, while the electrical contact resistance could be reduced by two orders of magnitude by addition of a-C:H phase to purely carbidic films. The present films are promising candidates for sliding electrical contact applications.

    sted, utgiver, år, opplag, sider
    Elsevier: , 2014
    Emneord
    Direct current magnetron sputtering, High power impulse magnetron sputtering, Reactive sputtering, Amorphous chromium carbide, Solid lubricant, Contact resistance
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-240742 (URN)10.1016/j.surfcoat.2014.06.069 (DOI)000347584300045 ()
    Konferanse
    The 41st International Conference on Metallurgical Coatings and Thin Films, APR 28-MAY 02, 2014, San Diego, CA
    Forskningsfinansiär
    Swedish Foundation for Strategic Research Swedish Research Council
    Tilgjengelig fra: 2015-01-08 Laget: 2015-01-08 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    3. Structure and properties of Cr-C/Ag films deposited by magnetron sputtering
    Åpne denne publikasjonen i ny fane eller vindu >>Structure and properties of Cr-C/Ag films deposited by magnetron sputtering
    Vise andre…
    2015 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 281, s. 184-192Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Cr-C/Ag thin films with 0-14 at% Ag have been deposited by magnetron sputtering from elemental targets. The samples were analyzed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to study their structure and chemical bonding. A complex nanocomposite structure consisting of three phases; nanocrystalline Ag, amorphous CrCx and amorphous carbon is reported. The carbon content in the amorphous carbide phase was determined to be 32-33 at% C, independent of Ag content Furthermore, SEM and XPS results showed higher amounts of Ag on the surface compared to the bulk. The hardness and Young's modulus were reduced from 12 to 8 GPa and from 270 to 170 GPa, respectively, with increasing Ag content. The contact resistance was found to decrease with Ag addition, with the most Ag rich sample approaching the values of an Ag reference sample. Initial tribological tests gave friction coefficients in the range of 0.3 to 0.5, with no clear trends. Annealing tests show that the material is stable after annealing at 500 degrees C for 1 h, but not after annealing at 800 degrees C for 1 h. In combination, these results suggest that sputtered Cr-C/Ag films could be potentially applicable for electric contact applications.

    sted, utgiver, år, opplag, sider
    Elsevier, 2015
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot oorganisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-247276 (URN)10.1016/j.surfcoat.2015.09.054 (DOI)000366072200024 ()
    Forskningsfinansiär
    Swedish Foundation for Strategic Research , RMA11-0029Swedish Research Council, 621-2011-3492
    Tilgjengelig fra: 2015-03-16 Laget: 2015-03-16 Sist oppdatert: 2017-12-04bibliografisk kontrollert
    4. The influence of nanoeffects on the oxidation of magnetron sputtered Cr-C/Ag thin films containing silver nanoparticles
    Åpne denne publikasjonen i ny fane eller vindu >>The influence of nanoeffects on the oxidation of magnetron sputtered Cr-C/Ag thin films containing silver nanoparticles
    2017 (engelsk)Inngår i: Chemelectrochem, ISSN 2196-0216, Vol. 4, nr 2, s. 418-429Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Well-controlled functionalization of carbide-based nanocomposite films with noble-metal surface nanoparticles of different sizes may lead to new materials with novel multifunctional properties. In this work, magnetron sputtering was used to deposit nanocomposite films comprising amorphous chromium carbide (a-CrCx), amorphous carbon (a-C), and a minority of silver in the form of embedded nanoclusters. Up to 510(10) surface nanoparticles per cm(2) with different size distributions were also found to be formed, owing to the diffusion of silver from the bulk of the film. The influences of these conductive nanoparticles on the electrochemical behavior of the films were investigated in dilute sulfuric acid. Although silver is a noble metal, the oxidation potential of the nanoparticles was about 0.4V more negative than the Ag+/Ag standard potential, meaning that the nanoparticles were oxidized in the Cr passive potential region. While this effect can mainly be explained by a low concentration of Ag+ in the electrolyte, the sizes of the nanoparticles and interactions with the matrix were also found to be important. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to analyze the surface chemistries. As Ag can be replaced by other noble metals, the concept is of general interest for further studies.

    Emneord
    Nanoelectrochemistry, Noble metals, Carbides, Nanoparticles, Thin films
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-302060 (URN)10.1002/celc.201600615 (DOI)000394905900026 ()
    Forskningsfinansiär
    Swedish Foundation for Strategic Research Swedish Research Council
    Tilgjengelig fra: 2016-08-29 Laget: 2016-08-29 Sist oppdatert: 2017-04-25bibliografisk kontrollert
    5. Passive films on nanocomposite carbide coatings for electrical contact applications
    Åpne denne publikasjonen i ny fane eller vindu >>Passive films on nanocomposite carbide coatings for electrical contact applications
    2017 (engelsk)Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, nr 13, s. 8231-8246Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Nanocomposite transition metal carbide/amorphous carbon coatings (Me-C/a-C) deposited by magnetron sputtering have excellent electrical contact properties. The contact resistance can be as low as that of noble metal coatings, although it is known to vary by several orders of magnitude depending on the deposition conditions. We have investigated a nanocrystalline niobium carbide/amorphous carbon (NbC (x) /a-C:H) model system aiming to clarify factors affecting the contact resistance for this group of contact materials. For the first time, the surface chemistry is systematically studied, by angle-resolved X-ray photoelectron spectroscopy, and in extension how it can explain the contact resistance. The coatings presented a mean oxide thickness of about 1 nm, which could be grown to 8 nm by annealing. Remarkably, the contact resistances covered four orders of magnitude and were found to be exponentially dependent on the mean oxide thickness. Moreover, there is an optimum in the amount of a-C:H phase where the contact resistance drops very significantly and it is thus important to not only consider the mean oxide thickness. To explain the results, a model relying on surface chemistry and contact mechanics is presented. The lowest contact resistance of a nanocomposite matched that of a gold coating at 1 N load (vs. gold), and such performance has previously not been demonstrated for similar nanocomposite materials, highlighting their useful properties for electrical contact applications.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-302061 (URN)10.1007/s10853-017-1039-0 (DOI)000399422000050 ()
    Forskningsfinansiär
    Swedish Foundation for Strategic Research VINNOVASwedish Research Council, VR 2011-3492
    Tilgjengelig fra: 2016-08-29 Laget: 2016-08-29 Sist oppdatert: 2017-05-23bibliografisk kontrollert
    6. Optical methods to quantify amorphous carbon in carbide-based nanocomposite coatings
    Åpne denne publikasjonen i ny fane eller vindu >>Optical methods to quantify amorphous carbon in carbide-based nanocomposite coatings
    2017 (engelsk)Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 638, s. 291-297Artikkel i tidsskrift (Annet vitenskapelig) Published
    Abstract [en]

    We report how the total carbon content and the amorphous carbon (a-C) phase fraction in transition metal carbide/a-C nanocomposite coatings can be obtained using optical methods, which are much more practical for industrial use than conventional X-ray photoelectron spectroscopy. A large set of carbon-containing nanocomposite coatings deposited using different magnetron sputtering techniques were analyzed by X-ray photoelectron spectroscopy, reflectance spectrophotometry, and spectroscopic ellipsometry. The chemical composition and the a-C phase fraction were determined by X-ray photoelectron spectroscopy for each coating and results are presented for the Ti-C, Cr-C, and Nb-C systems. The composition and the a-C phase fraction are correlated to optical reflectance in the visible range, by parametrization in L*a*b* color space, and by ellipsometry primary data. Results show that it is possible to rapidly estimate the composition and the a-C fraction using these optical methods. We propose that optical methods have promising use in the industry as a cost-efficient technique for characterization of carbide-based coatings.

    sted, utgiver, år, opplag, sider
    Elsevier, 2017
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-302062 (URN)10.1016/j.tsf.2017.07.053 (DOI)000411775900038 ()
    Tilgjengelig fra: 2016-08-29 Laget: 2016-08-29 Sist oppdatert: 2017-12-20bibliografisk kontrollert
  • 42.
    Olander, Petra
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Eskildsen S., Svend
    Fogh W., Jesper
    Hollman, P.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Testing scuffing resistance of materials for marine 2-stroke engines: Difficulties with lab scale testing of a complex phenomenon2014Inngår i: Proceedings of 16th Nordic Symposium on Tribology: NORDTRIB 2014 / [ed] Sivebæk, Ion Marius, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Optimising sliding materials of marine two-stroke diesel engine cylinders to reduce the risk for scuffing is imperative because of the high costs associated with replacing the cylinder liner. But how can a complex and poorly understood phenomenon such as scuffing be tested? In this study, the potential to enable material selection based on lab tests is investigated. Experience from ship operation is combined with analysis of lab scale scuffing tests to evaluate the possibilities of gaining applicable knowledge from scuffing testing. Two piston ring materials, a grey cast iron and a plasma sprayed cermet coating, both currently used in engines, were tested. Each of the materials was tested with two surface characters, achieved by run-in in a real engine or by grinding. The ranking of the two materials proved to differ between the two surface characters. In the tests, scuffing could only be detected when all oil had become removed from the contact by being adsorbed by wear debris agglomerates. This, and other critical mechanisms behind scuffing in the tests are thoroughly discussed and compared to possible mechanisms taking place in the engine.

  • 43.
    Olsson, Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Carlsson, Daniel O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nyström, Gustav
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Sjödin, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Strømme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Influence of the cellulose substrate on the electrochemical properties of paper-based polypyrrole electrode materials2012Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 47, nr 13, s. 5317-5325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of the cellulose substrate on the electrochemical performance of supercapacitor electrode materials made of polypyrrole (PPy) and cellulose is investigated. Composites were synthesized by chemical polymerization of pyrrole on dispersed fibers of cellulose from Cladophora algae and dispersed wood cellulose-based commercial filter papers, respectively, as well as on Cladophora cellulose and filter paper sheets. The resulting composites, which were characterized using scanning electron microscopy, cyclic voltammetry, and elemental analysis, were found to exhibit specific charge capacities proportional to the PPy content of the composites. The highest specific capacity (i.e., 171 C/g composite or 274 C/g PPy) was obtained for composites made from dispersed Cladophora cellulose fibers. The higher specific capacities for the Cladophora cellulose composites can be explained by the fact that the Cladophora cellulose fibers were significantly thinner than the wood cellulose fibers. While the PPy was mainly situated on the surface of the Cladophora cellulose fibers, a significant part of the PPy was found to be present within the wood fibers of the filter paper-based composites. The latter can be ascribed to a higher accessibility of the aqueous pyrrole solution to the wood-based fibers as compared to the highly crystalline algae based cellulose fibers. The present results clearly show that the choice of the cellulose substrate is important when designing electrode materials for inexpensive, flexible and environmentally friendly paper-based energy storage devices.

  • 44.
    Oskarsson, Jakob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Tribological testing of drill bit inserts2011Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis work sought to find a tribological testing method suitable for cementedcarbide drill bit inserts used when drilling rock. A review of the literature publishedon the matter showed that there are quite a few test methods developed for wearstudies with cemented carbides, but most of them were not designed for the rockdrilling industry. Published studies performed with the found methods and articleswith analyzed field tests have been studied. It is generally agreed upon that the stepsof wear is that the binder disappears first, followed by removal of carbide grains. Themechanisms of binder phase and carbide grain removal is somewhat debated, butalmost every study observes fracture of the carbide grains. The wear test created inthis thesis was shown to give wear linear with time, but not with load. The newmethod was shown to be capable of distinguishing between different cementedcarbides worn in three body abrasion against different rocks. Analysis of the wornsamples shows that there are similarities with bit inserts worn in field testing. Many ofthe observations made during the analysis are also similar to observations inliterature.

  • 45.
    Perraud, Simon
    et al.
    CEA LITEN, Grenoble, Frankrike.
    Quesnel, Etienne
    CEA LITEN, Grenoble, Frankrike.
    Parola, Stéphanie
    CEA LITEN, Grenoble, Frankrike.
    Barbé, Jeremy
    CEA LITEN, Grenoble, Frankrike, och Université de Toulouse, UPS, INPT, LAPLACE, Frankrike.
    Muffato, Viviane
    CEA LITEN, Grenoble, Frankrike.
    Faucherand, Pascal
    CEA LITEN, Grenoble, Frankrike.
    Morin, Christine
    CEA LITEN, Grenoble, Frankrike.
    Jarolimek, Karol
    Photovoltaic Materials and Devices, Delft University of Technology, Nederländerna.
    Van Swaaij, Rene A. C. M. M.
    Photovoltaic Materials and Devices, Delft University of Technology, Nederländerna.
    Zeman, Miro
    Photovoltaic Materials and Devices, Delft University of Technology, Nederländerna.
    Richards, Stephen
    SAFC Hitech, Bromborough, Merseyside, UK.
    Kingsley, Andrew
    SAFC Hitech, Bromborough, Merseyside, UK.
    Doyle, Hugh
    Tyndall National Institute, University College Cork, Irland.
    Linehan, Keith
    Tyndall National Institute, University College Cork, Irland.
    O'Brien, Shane
    Tyndall National Institute, University College Cork, Irland.
    Povey, Ian M.
    Tyndall National Institute, University College Cork, Irland.
    Pemble, Martyn
    Tyndall National Institute, University College Cork, Irland.
    Ling, Xie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Leifer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Makasheva, Kremena
    Université de Toulouse, UPS, INPT, LAPLACE, Frankrike.
    Despax, Bernard
    Université de Toulouse, UPS, INPT, LAPLACE, Frankrike.
    Silicon nanocrystals: Novel synthesis routes for photovoltaic applications2013Inngår i: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 210, nr 4, s. 649-657Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel processes were developed for fabricating silicon nanocrystals and nanocomposite materials which could be used as absorbers in third generation photovoltaic devices. A conventional high-temperature annealing technique was studied as a reference process, with some new insights in crystallisation mechanisms. Innovative methods for silicon nanocrystal synthesis at much lower temperature were demonstrated, namely chemical vapour deposition (CVD), physical vapour deposition (PVD) and aerosol-assisted CVD. Besides the advantage of low substrate temperature, these new techniques allow to fabricate silicon nanocrystals embedded in wide bandgap semiconductor host matrices, with a high density and a narrow size dispersion.

  • 46.
    Procter, Philip
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Pujari-Palmer, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap. Uppsala University.
    Hulsart Billström, Gry
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Larsson, Sune
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Ortopedi.
    Insley, Gerard
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Designing A Commercial Biomaterial For A Specific Unmet Clinical Need –: An Adhesive Odyssey2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There are clinical situations in fracture repair, e.g. osteochondral fragments, where current implant hardware is insufficient. The proposition of an adhesive enabling fixation and healing has been considered but no successful candidate has emerged thus far. The many preclinical and few clinical attempts include fibrin glue, mussel adhesive and even “Kryptonite” (US bone void filler). The most promising recent attempts are based on phosphorylating amino acids, part of a common cellular adhesion mechanism linking mussels, caddis fly larvae, and mammals. Rapid high bond strength development in the wetted fatty environment of fractured bone, that is sustained during biological healing, is challenging to prove both safety and efficacy. Additionally, there are no “predicate” preclinical animal and human models which led the authors to develop novel evaluations for an adhesive candidate “OsStictm” based on calcium salts and amino acids. Adhesive formulations were evaluated in both soft (6/12 weeks) and hard tissue (3,7,10,14 & 42 days) safety studies in murine models. The feasibility of a novel adhesiveness test, initially proven in murine cadaver femoral bone, is being assessed in-vivo (3,7,10,14 & 42 days) in bilateral implantations with a standard tissue glue as the control. In parallel an ex-vivo human bone model using freshly harvested human donor bone is under development to underwrite the eventual clinical application of such an adhesive. This is part of a risk mitigation project bridging between laboratory biomaterial characterisation and a commercial biomaterial development where safety and effectiveness have to meet today´s new medical device requirements.

  • 47.
    Procter, Philip
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Pujari-Palmer, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Hulsart-Billstrom, Gry
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wenner, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Insley, Gerard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Larsson, Sune
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Ortopedi.
    Engqvsit, Hakan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    A biomechanical test model for evaluating osseous and osteochondral tissue adhesives.Inngår i: BMC Biomedical engineering, ISSN 2524-4426Artikkel i tidsskrift (Fagfellevurdert)
  • 48.
    Pujari-Palmer, Michael
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap. 0000-0001-7004-2853.
    Guo, Hua
    Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden.
    Wenner, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Autefage, Hélène
    Karolinska Inst, Dept Med Biochem & Biophys, Stockholm, Sweden.
    Spicer, Christopher D.
    Karolinska Inst, Dept Med Biochem & Biophys, Stockholm, Sweden.
    Stevens, Molly M.
    Karolinska Inst, Dept Med Biochem & Biophys, Stockholm, Sweden; Imperial Coll London, Dept Bioengn, Dept Mat, London, England; Imperial Coll London, Inst Biomed Engn, London, England.
    Omar, Omar
    Univ Gothenburg, Inst Clin Sci, Dept Biomat, Gothenburg, Sweden.
    Thomsen, Peter
    Univ Gothenburg, Inst Clin Sci, Dept Biomat, Gothenburg, Sweden.
    Edén, Mattias
    Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden.
    Insley, Gerard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Procter, Philip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    A Novel Class of Injectable Bioceramics that Glue Tissues and Biomaterials2018Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, nr 12, artikkel-id 2492Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Calcium phosphate cements (CPCs) are clinically effective void fillers that are capable of bridging calcified tissue defects and facilitating regeneration. However, CPCs are completely synthetic/inorganic, unlike the calcium phosphate that is found in calcified tissues, and they lack an architectural organization, controlled assembly mechanisms, and have moderate biomechanical strength, which limits their clinical effectiveness. Herein, we describe a new class of bioinspired CPCs that can glue tissues together and bond tissues to metallic and polymeric biomaterials. Surprisingly, alpha tricalcium phosphate cements that are modified with simple phosphorylated amino acid monomers of phosphoserine (PM-CPCs) bond tissues up to 40-fold stronger (2.5–4 MPa) than commercial cyanoacrylates (0.1 MPa), and 100-fold stronger than surgical fibrin glue (0.04 MPa), when cured in wet-field conditions. In addition to adhesion, phosphoserine creates other novel properties in bioceramics, including a nanoscale organic/inorganic composite microstructure, and templating of nanoscale amorphous calcium phosphate nucleation. PM-CPCs are made of the biocompatible precursors calcium, phosphate, and amino acid, and these represent the first amorphous nano-ceramic composites that are stable in liquids.

  • 49.
    Rostvall, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Potential Induced Degradation of CIGS Solar Cells2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]