uu.seUppsala University Publications
Change search
Refine search result
1234567 1 - 50 of 1009
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Absil, Oliver
    et al.
    Université de Liège, Belgium.
    Mawet, Dimitri
    California Institute of Technology/Jet Propulsion Laboratory, USA.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Carlomagno, Brunella
    Université de Liège, Belgium.
    Christiaens, Valentin
    Universidad de Chile, Chile.
    Defrère, Denis
    Université de Liège, Belgium.
    Delacroix, Christian
    Cornell University, USA.
    Femenía Castellá, Bruno
    W. M. Keck Observatory, USA.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Girard, Julien
    European Southern Observatory, Chile.
    Gómez González, Carlos A.
    Université de Liège, Belgium.
    Habraken, Serge
    Université de Liège, Belgium.
    Hinz, Philip M.
    University of Arizona, USA.
    Huby, Elsa
    Université de Liège, Belgium.
    Jolivet, Aissa
    Université de Liège, Belgium.
    Matthews, Keith
    California Institute of Technology, USA.
    Milli, Julien
    European Southern Observatory, USA.
    Orban de Xivry, Gilles
    Université de Liège, Belgium.
    Pantin, Eric
    Université Paris Diderot, France.
    Piron, Pierre
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Reggiani, Maddalena
    Université de Liège, Belgium.
    Ruane, Garreth J.
    California Institute of Technology, USA.
    Serabyn, Eugene
    Jet Propulsion Laboratory, USA.
    Surdej, Jean
    Université de Liège, Belgium.
    Tristram, Konrad R. W.
    European Southern Observatory, Chile.
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wertz, Olivier
    Université de Liège, Belgium.
    Wizinowich, Peter
    W. M. Keck Observatory, USA.
    Three years of harvest with the vector vortex coronagraph in the thermal infrared2016In: Ground-Based and Airborne Instrumentation for Astronomy VI: 26-30 June 2016, Edinburgh, United Kingdom / [ed] Christopher J Evans, SPIE - International Society for Optical Engineering, 2016, Vol. 9908, 1-14 p., 99080Q-1Conference paper (Refereed)
    Abstract [en]

    For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to be used in the thermal infrared (ranging from 3 to 13 μm). Our AGPMs were first installed on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and Keck/NIRC2 in 2015. In this paper, we review the development, commissioning, on-sky performance, and early scientific results of these new coronagraphic modes and report on the lessons learned. We conclude with perspectives for future developments and applications.

  • 2. Absil, Olivier
    et al.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mawet, Dimitri
    Carlomagno, Brunella
    Christiaens, Valentin
    Delacroix, Christian
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gomez Gonzales, Carlos
    Habraken, Serge
    Jolivet, Aïssa
    Piron, Pierre
    Van Droogenbroeck, Marc
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Absil, Pierre-Antoine
    Boccaletti, Anthony
    Baudoz, Pierre
    Defrère, Dennis
    Milli, Julien
    Surdej, Sean
    Optimized, high performance vortex coronagraphs for E-ELT instruments2014Conference paper (Refereed)
  • 3. Absil, Olivier
    et al.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mawet, Dimitri
    Carlomagno, Brunella
    Christiaens, Valentin
    Delacroix, Christian
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gomez Gonzales, Carlos
    Habraken, Serge
    Jolivet, Aïssa
    Piron, Pierre
    Van Droogenbroeck, Marc
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Absil, Pierre-Antoine
    Boccaletti, Anthony
    Baudoz, Pierre
    Defrère, Dennis
    Milli, Julien
    Surdej, Sean
    Reaching the diffraction limit with the vortex coronagraph2014Conference paper (Refereed)
  • 4. Absil, Olivier
    et al.
    Mawet, Dimitri
    Delacroix, Christian
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Habraken, Serge
    Surdej, Jean
    Absil, Pierre-Antoine
    Carlomagno, Brunella
    Christiaens, Valentin
    Defrere, Denis
    Gonzalez, Carlos Gomez
    Huby, Elsa
    Jolivet, Aissa
    Milli, Julien
    Piron, Pierre
    Catalan, Ernesto Vargas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Van Droogenbroeck, Marc
    The VORTEX project: first results and perspectives2014In: Adaptive Optics Systems IV, 2014, 91480MConference paper (Refereed)
    Abstract [en]

    Vortex coronagraphs are among the most promising solutions to perform high contrast imaging at small angular separations from bright stars. They feature a very small inner working angle (down to the diffraction limit of the telescope), a clear 360 degree discovery space, have demonstrated very high contrast capabilities, are easy to implement on high-contrast imaging instruments, and have already been extensively tested on the sky. Since 2005, we have been designing, developing and testing an implementation of the charge-2 vector vortex phase mask based on concentric sub-wavelength gratings, referred to as the Annular Groove Phase Mask (AGPM). Science-grade mid-infrared AGPMs were produced in 2012 for the first time, using plasma etching on synthetic diamond substrates. They have been validated on a coronagraphic test bench, showing broadband peak rejection up to 500: 1 in the L band, which translates into a raw contrast of about 6 x 10(-5) at 2 lambda/D. Three of them have now been installed on world-leading diffraction-limited infrared cameras, namely VLT/NACO, VLT/VISIR and LBT/LMIRCam. During the science verification observations with our L-band AGPM on NACO, we observed the beta Pictoris system and obtained unprecedented sensitivity limits to planetary companions down to the diffraction limit (0 : 1 0 0). More recently, we obtained new images of the HR 8799 system at L band during the AGPM first light on LMIRCam. After reviewing these first results obtained with mid-infrared AGPMs, we will discuss the short-and mid-term goals of the on-going VORTEX project, which aims to improve the performance of our vortex phase masks for future applications on second-generation high-contrast imager and on future extremely large telescopes (ELTs). In particular, we will briefly describe our current efforts to improve the manufacturing of mid-infrared AGPMs, to push their operation to shorter wavelengths, and to provide deeper starlight extinction by creating new designs for higher topological charge vortices. Within the VORTEX project, we also plan to develop new image processing techniques tailored to coronagraphic images, and to study some pre- and post-coronagraphic concepts adapted to the vortex coronagraph in order to reduce scattered starlight in the final images.

  • 5. Absil, Olivier
    et al.
    Mawet, Dimitri
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Habraken, Serge
    Surdej, Jean
    Absil, Pierre-Antoine
    Carlomagno, Brunella
    Christiaens, Valentin
    Defrère, Denis
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Girard, Julien
    Gomez Gonzalez, Carlos
    Hinz, Philip
    Huby, Elsa
    Jolivet, Aïssa
    Milli, Julien
    Pantin, Eric
    Ruane, Garreth
    Serabyn, Eugene
    Van Droogenbroeck, Marc
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wertz, Olivier
    An update on the VORTEX project2015In: Techniques and Instrumentation for Detection of Exoplanets VII, 2015, Vol. 9605Conference paper (Refereed)
    Abstract [en]

    In this talk, we will review the on-going activities within the VORTEX teamat the University of Liège and Uppsala University. The VORTEX project aimsto design, manufacture, test, and exploit vector vortex phase masks madeof sub-wavelength gratings (aka the Annular Groove Phase Mask, AGPM)for the direct detection and characterization of extrasolar planets. This talkwill specifically report on the commissioning of several AGPMs on infraredcameras equipping 10-m class telescopes, including the VLT, the LBT andthe Keck. We will describe the in-lab and on-sky performance of the AGPMs,and discuss first scientific observations. We will also report on the lessonslearned from the on-sky operation of our vortices, and discuss ways toimprove their performance. The potential of our coronagraphic devices inthe context of future extremely large telescopes and space missions will alsobe addressed.

  • 6.
    Aiso, Toshiharu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Workpiece steels protecting cutting tools from wear: A study of the effects of alloying elements on material transfer and coating damage mechanisms2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The vision of this thesis is to improve the machinability of workpiece steels. Workpiece material frequently transfers to the cutting tools during machining, and the transfer layers then forming on the tools may give both good and bad effects on machining performance and tool life. The objective of this work is to understand the effects of alloying element additions to workpiece steels on material transfer and the roles of the formed transfer layers on friction characteristics and wear of tools.

    To isolate and study the influence of the individual alloying elements, model steels are specifically designed. These steels include one reference with C as the only alloying element and others alloyed also with single additions or combined additions of 1 mass% Si, Mn, Cr and Al. The experiments are performed using both a sliding test, simulating the material transfer in milling, and a turning test.

    In a sliding contact, the mode of transfer is strongly dependent on the normal load and sliding speed. Material transfer initiates extremely fast, in less than 0.025 s, and characteristic transfer layers develop during the first few seconds. The different steel compositions result in the formation of different types of oxides in the transfer layers. At the workpiece/tool interface where the conditions involve high temperature, high pressure and low oxygen supply, easily oxidized alloying elements in the steel are preferentially transferred, enriched and form a stable oxide on the tool surface. The degree of enrichment of the alloying elements in the oxides is strongly related to their tendencies to become oxidized.

    The difference in melting temperature of the oxides, and thus the tendency to soften during sliding, explains the difference in the resulting friction coefficient. The widest differences in friction coefficients are found between the Si and Al additions. A Si containing oxide shows the lowest friction and an Al containing oxide the highest.

    The damage mechanism of coated tools is chiefly influenced by the form and shear strength of the transferred material. Absence of transfer layer or non-continuous transferred material leads to continuous wear of the coating. Contrastingly, continuous transfer layers protect it from wear. However, transfer layers with very high shear strength result in high friction heat and a large amount of steel transfer. This leads to rapid coating cracking or adhesive wear.

    List of papers
    1. Influence of contact parameters on material transfer from steel to TiN coated tool – optimisation of a sliding test for simulation of material transfer in milling
    Open this publication in new window or tab >>Influence of contact parameters on material transfer from steel to TiN coated tool – optimisation of a sliding test for simulation of material transfer in milling
    2016 (English)In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 10, no 3, 107-116 p.Article in journal (Refereed) Published
    Abstract [en]

    Sliding between crossed cylinders, one large work material cylinder and one smaller coated tool cylinder, can be used to simulate the contact between a chip and the rake face of a cutting tool. However accurate simulations require the mode of material transfer in the test to match that in real machining. The mode is strongly dependent on normal load and sliding speed, and it is classified into four types; negligible oxide, only iron oxide, iron oxide and alloy oxide, and metallic transfer with coating cracking. A high load proved to be most important to accurately simulate the mode and area of material transfer occurring in milling. The diameter of the work material cylinder influences the shape of the contact mark, but has no influence on the mode of transfer. This means smaller work material diameters can favorably be used, reducing costs and facilitating handling during both tests and analysis.

    Keyword
    Sliding test, Material transfer, Milling, Coating
    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-299592 (URN)10.1080/17515831.2016.1202548 (DOI)
    Available from: 2016-07-23 Created: 2016-07-23 Last updated: 2016-11-29
    2. Effect of Si and Cr additions to carbon steel on material transfer in a steel/TiN coated tool sliding contact
    Open this publication in new window or tab >>Effect of Si and Cr additions to carbon steel on material transfer in a steel/TiN coated tool sliding contact
    2016 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 97, 337-348 p.Article in journal (Refereed) Published
    Abstract [en]

    A crossed cylinders sliding test, simulating the contact between the chip and the tool in machining, is used to evaluate material transfer and friction characteristics of a TiN coating against specifically designed model steels. These include one base reference, only alloyed with C (Base steel) and two alloyed also with 1 mass% Si or Cr. When sliding against the Base steel, an Fe-O layer is formed on the coating. Against the Si and Cr alloyed steels, Fe-Si-O and Fe-Cr-O layers are formed. In these oxides, Si and Cr are enriched, i.e. preferentially transferred from the steels. Compared to the Base steel, the friction coefficient is significantly lower against the Si alloyed steel and higher against the Cr alloyed steel.

    Keyword
    Transfer, Coating, Sliding
    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-284092 (URN)10.1016/j.triboint.2016.01.032 (DOI)000374194900035 ()
    Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2016-10-26Bibliographically approved
    3. Influence of Mn and Al additions to carbon steel on material transfer and coating damage mechanism in a sliding contact between steel and TiN coated HSS tool
    Open this publication in new window or tab >>Influence of Mn and Al additions to carbon steel on material transfer and coating damage mechanism in a sliding contact between steel and TiN coated HSS tool
    2016 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 101, 414-424 p.Article in journal (Refereed) Published
    Abstract [en]

    A crossed cylinders sliding test, simulating the contact between the chip and the cutting tool, is used to evaluate material transfer, friction characteristics and coating damage of a TiN coated high speed steel against specifically designed model steels. These steels include one reference with C as the only alloy element (Base steel), and two alloyed also with 1 mass% Mn or Al. When sliding against the Base steel, an Fe–O layer forms on the coating and protects it from wear. Against the Mn alloyed steel, Fe–Mn–O forms, which has no protective effect. Against the Al alloyed steel, an almost pure Al–O layer forms. This leads to the highest friction, rapidly causing substrate softening and coating fracture.

    Keyword
    Transfer, Coating, Sliding
    National Category
    Tribology
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-294613 (URN)10.1016/j.triboint.2016.04.036 (DOI)000379563700044 ()
    Available from: 2016-05-25 Created: 2016-05-25 Last updated: 2016-10-26Bibliographically approved
    4. Effect of combined additions of Si, Mn, Cr and Al to carbon steel on material transfer in a steel/TiN coated tool sliding contact
    Open this publication in new window or tab >>Effect of combined additions of Si, Mn, Cr and Al to carbon steel on material transfer in a steel/TiN coated tool sliding contact
    (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed) Submitted
    Abstract [en]

    Material transferred from steel work materials onto the cutting tools largely affects tool life and machining performance. This material transfer is strongly influenced by the steel composition, and different alloying can have very different effects. Crossed cylinders sliding tests can be used to simulate the contact between the chip and the tool in machining. In this work such a test is used to evaluate material transfer and friction characteristics of a TiN coated tool sliding against five model steels. These model steels are especially designed to study the effects from specific combination of alloy elements, i.e. the steels, containing 0.55 mass% C and 1 mass% Si, are alloyed with one or more of 1 mass% Mn, Cr and Al. When using the steels alloyed without Al, Si-rich oxide layers are formed on the coating, resulting in a low friction coefficient. When using the steels alloyed with Al, almost pure Al–O layers are formed, resulting in a higher friction coefficient and rapid coating cracking. Essentially, the most easily oxidized alloy element is most strongly enriched in the oxide and decides the main mechanism of the material transfer and friction behavior.

    Keyword
    Sliding, Steel, PVD coatings, Cutting tools, Transfer
    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-306189 (URN)
    Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2016-10-26
    5. Effect of Si and Al additions to carbon steel on material transfer and coating damage mechanism in turning with CVD coated tools
    Open this publication in new window or tab >>Effect of Si and Al additions to carbon steel on material transfer and coating damage mechanism in turning with CVD coated tools
    2016 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 368-369, 379-389 p.Article in journal (Refereed) Published
    Abstract [en]

    Material transfer from the work materials to the tools strongly influences machining performance and tool life. The influence of Si and Al additions to carbon steel on the material transfer and coating wear in turning with CVD coated carbide tools is investigated. Three model steels are specifically designed to separately study the effects of the individual alloying elements: one reference steel with C as the only alloying element (Base steel), and two steels alloyed also with 1 mass% Si or Al. In the region around the depth of cut on the rake face, where the outside edge of the chip passes over the tool surface, the coating is worn mainly by abrasion when cutting the Base steel. When cutting the Si alloyed steel, an almost pure Si–O transfer layer covers the coating surface, which protects it from wear. When cutting the Al alloyed steel, an almost pure Al–O transfer layer forms on the coating. This layer promotes steel transfer and associated adhesive wear of the coating, which rapidly results in coating detachment and eventually causes notch wear. In the crater region, only the Al alloyed steel results in a transfer layer, an AlN layer that reduces the crater wear.

    Keyword
    Steel, CVD coatings, Cutting tools, Transfer
    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-306187 (URN)10.1016/j.wear.2016.10.011 (DOI)000390733400041 ()
    Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2017-08-08Bibliographically approved
  • 7.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of contact parameters on material transfer from steel to TiN coated tool – optimisation of a sliding test for simulation of material transfer in milling2016In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 10, no 3, 107-116 p.Article in journal (Refereed)
    Abstract [en]

    Sliding between crossed cylinders, one large work material cylinder and one smaller coated tool cylinder, can be used to simulate the contact between a chip and the rake face of a cutting tool. However accurate simulations require the mode of material transfer in the test to match that in real machining. The mode is strongly dependent on normal load and sliding speed, and it is classified into four types; negligible oxide, only iron oxide, iron oxide and alloy oxide, and metallic transfer with coating cracking. A high load proved to be most important to accurately simulate the mode and area of material transfer occurring in milling. The diameter of the work material cylinder influences the shape of the contact mark, but has no influence on the mode of transfer. This means smaller work material diameters can favorably be used, reducing costs and facilitating handling during both tests and analysis.

  • 8.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of combined additions of Si, Mn, Cr and Al to carbon steel on material transfer in a steel/TiN coated tool sliding contactIn: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed)
    Abstract [en]

    Material transferred from steel work materials onto the cutting tools largely affects tool life and machining performance. This material transfer is strongly influenced by the steel composition, and different alloying can have very different effects. Crossed cylinders sliding tests can be used to simulate the contact between the chip and the tool in machining. In this work such a test is used to evaluate material transfer and friction characteristics of a TiN coated tool sliding against five model steels. These model steels are especially designed to study the effects from specific combination of alloy elements, i.e. the steels, containing 0.55 mass% C and 1 mass% Si, are alloyed with one or more of 1 mass% Mn, Cr and Al. When using the steels alloyed without Al, Si-rich oxide layers are formed on the coating, resulting in a low friction coefficient. When using the steels alloyed with Al, almost pure Al–O layers are formed, resulting in a higher friction coefficient and rapid coating cracking. Essentially, the most easily oxidized alloy element is most strongly enriched in the oxide and decides the main mechanism of the material transfer and friction behavior.

  • 9.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of Si and Al additions to carbon steel on material transfer and coating damage mechanism in turning with CVD coated tools2016In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 368-369, 379-389 p.Article in journal (Refereed)
    Abstract [en]

    Material transfer from the work materials to the tools strongly influences machining performance and tool life. The influence of Si and Al additions to carbon steel on the material transfer and coating wear in turning with CVD coated carbide tools is investigated. Three model steels are specifically designed to separately study the effects of the individual alloying elements: one reference steel with C as the only alloying element (Base steel), and two steels alloyed also with 1 mass% Si or Al. In the region around the depth of cut on the rake face, where the outside edge of the chip passes over the tool surface, the coating is worn mainly by abrasion when cutting the Base steel. When cutting the Si alloyed steel, an almost pure Si–O transfer layer covers the coating surface, which protects it from wear. When cutting the Al alloyed steel, an almost pure Al–O transfer layer forms on the coating. This layer promotes steel transfer and associated adhesive wear of the coating, which rapidly results in coating detachment and eventually causes notch wear. In the crater region, only the Al alloyed steel results in a transfer layer, an AlN layer that reduces the crater wear.

  • 10.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of Si and Cr additions to carbon steel on material transfer in a steel/TiN coated tool sliding contact2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 97, 337-348 p.Article in journal (Refereed)
    Abstract [en]

    A crossed cylinders sliding test, simulating the contact between the chip and the tool in machining, is used to evaluate material transfer and friction characteristics of a TiN coating against specifically designed model steels. These include one base reference, only alloyed with C (Base steel) and two alloyed also with 1 mass% Si or Cr. When sliding against the Base steel, an Fe-O layer is formed on the coating. Against the Si and Cr alloyed steels, Fe-Si-O and Fe-Cr-O layers are formed. In these oxides, Si and Cr are enriched, i.e. preferentially transferred from the steels. Compared to the Base steel, the friction coefficient is significantly lower against the Si alloyed steel and higher against the Cr alloyed steel.

  • 11.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of Mn and Al additions to carbon steel on material transfer and coating damage mechanism in a sliding contact between steel and TiN coated HSS tool2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 101, 414-424 p.Article in journal (Refereed)
    Abstract [en]

    A crossed cylinders sliding test, simulating the contact between the chip and the cutting tool, is used to evaluate material transfer, friction characteristics and coating damage of a TiN coated high speed steel against specifically designed model steels. These steels include one reference with C as the only alloy element (Base steel), and two alloyed also with 1 mass% Mn or Al. When sliding against the Base steel, an Fe–O layer forms on the coating and protects it from wear. Against the Mn alloyed steel, Fe–Mn–O forms, which has no protective effect. Against the Al alloyed steel, an almost pure Al–O layer forms. This leads to the highest friction, rapidly causing substrate softening and coating fracture.

  • 12.
    Ajalloueian, Fatemeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Tavanai, Hossein
    Hilborn, Jons
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wickham, Abeni
    Arpanaei, Ayyoob
    Emulsion Electrospinning as an Approach to Fabricate PLGA/Chitosan Nanofibers for Biomedical Applications2014In: BioMed Research International, ISSN 2314-6133, Vol. 2014, 475280- p.Article in journal (Refereed)
    Abstract [en]

    Novel nanofibers from blends of polylactic-co-glycolic acid (PLGA) and chitosan have been produced through an emulsion electrospinning process. The spinning solution employed polyvinyl alcohol (PVA) as the emulsifier. PVA was extracted from the electrospun nanofibers, resulting in a final scaffold consisting of a blend of PLGA and chitosan. The fraction of chitosan in the final electrospun mat was adjusted from 0 to 33%. Analyses by scanning and transmission electron microscopy show uniform nanofibers with homogenous distribution of PLGA and chitosan in their cross section. Infrared spectroscopy verifies that electrospun mats contain both PLGA and chitosan. Moreover, contact angle measurements show that the electrospun PLGA/chitosanmats are more hydrophilic than electrospun mats of pure PLGA. Tensile strengths of 4.94 MPa and 4.21 MPa for PLGA/chitosan in dry and wet conditions, respectively, illustrate that the polyblend mats of PLGA/chitosan are strong enough for many biomedical applications. Cell culture studies suggest that PLGA/chitosan nanofibers promote fibroblast attachment and proliferation compared to PLGA membranes. It can be assumed that the nanofibrous composite scaffold of PLGA/chitosan could be potentially used for skin tissue reconstruction.

  • 13.
    Ajaxon, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Can Bone Void Fillers Carry Load?: Behaviour of Calcium Phosphate Cements Under Different Loading Scenarios2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Calcium phosphate cements (CPCs) are used as bone void fillers and as complements to hardware in fracture fixation. The aim of this thesis was to investigate the possibilities and limitations of the CPCs’ mechanical properties, and find out if these ceramic bone cements can carry application-specific loads, alone or as part of a construct. Recently developed experimental brushite and apatite cements were found to have a significantly higher strength in compression, tension and flexion compared to the commercially available CPCs chronOS™ Inject and Norian® SRS®. By using a high-resolution measurement technique the elastic moduli of the CPCs were determined and found to be at least twice as high compared to earlier measurements, and closer to cortical bone than trabecular bone. Using the same method, Poisson's ratio for pure CPCs was determined for the first time. A non-destructive porosity measurement method for wet brushite cements was developed, and subsequently used to study the porosity increase during in vitro degradation. The compressive strength of the experimental brushite cement was still higher than that of trabecular bone after 25 weeks of degradation, showing that the cement can carry high loads over a time span sufficiently long for a fracture to heal. This thesis also presents the first ever fatigue results for acidic CPCs, and confirms the importance of testing the materials under cyclic loading as the cements may fail at stress levels much lower than the material’s quasi-static compressive strength. A decrease in fatigue life was found for brushite cements containing higher amounts of monetite. Increasing porosity and testing in a physiological buffer solution (PBS), rather than air, also decreased the fatigue life. However, the experimental brushite cement had a high probability of surviving loads found in the spine when tested in PBS, which has previously never been accomplished for acidic CPCs. In conclusion, available brushite cements may be able to carry the load alone in scenarios where the cortical shell is intact, the loading is mainly compressive, and the expected maximum stress is below 10 MPa. Under such circumstances this CPC may be the preferred choice over less biocompatible and non-degradable materials.

    List of papers
    1. Mechanical Properties of Brushite Calcium Phosphate Cements
    Open this publication in new window or tab >>Mechanical Properties of Brushite Calcium Phosphate Cements
    2017 (English)In: The World Scientific Encyclopedia of Nanomedicine and Bioengineering II: Bioimplants, Regenerative Medicine, and Nano-Cancer Diagnosis and Phototherapy: Volume 3: Design of Bioactive Materials for Bone Repair and Regeneration / [ed] Shi, D., Singapore: World Scientific Pte Ltd. , 2017Chapter in book (Refereed)
    Place, publisher, year, edition, pages
    Singapore: World Scientific Pte Ltd., 2017
    National Category
    Biomaterials Science Ceramics Medical Materials
    Identifiers
    urn:nbn:se:uu:diva-316712 (URN)978-981-4667-58-6 (ISBN)
    Funder
    Swedish Research Council, GA 621-2011-6258
    Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-03-22
    2. Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
    Open this publication in new window or tab >>Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
    Show others...
    2016 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 60, 617-627 p.Article in journal (Refereed) 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.

    Keyword
    Calcium phosphate cement; Brushite; Apatite; Compressive strength; Tensile strength; Flexural strength
    National Category
    Ceramics
    Identifiers
    urn:nbn:se:uu:diva-284218 (URN)10.1016/j.jmbbm.2016.03.028 (DOI)000378969100055 ()27082025 (PubMedID)
    Funder
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-2047Swedish Research Council, 621-2011-6258
    Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2017-03-22Bibliographically approved
    3. Elastic properties and strain-to-crack-initation of calcium phosphate bone cements: revelations of a high-resolution measurement technique
    Open this publication in new window or tab >>Elastic properties and strain-to-crack-initation of calcium phosphate bone cements: revelations of a high-resolution measurement technique
    Show others...
    2017 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 74, 428-437 p.Article in journal (Refereed) Published
    Abstract [en]

    Calcium phosphate cements (CPCs) should ideally have mechanical properties similar to those of the bone tissue the material is used to replace or repair. Usually, the compressive strength of the CPCs is reported and, more rarely, the elastic modulus. Conversely, scarce or no data are available on Poisson's ratio and strain-to-crack-initiation. This is unfortunate, as data on the elastic response is key to, e.g., numerical model accuracy. In this study, the compressive behaviour of brushite, monetite and apatite cements was fully characterised. Measurement of the surface strains was done using a digital image correlation (DIC) technique, and compared to results obtained with the commonly used built-in displacement measurement of the materials testers. The collected data showed that the use of fixed compression platens, as opposed to spherically seated ones, may in some cases underestimate the compressive strength by up to 40%. Also, the built-in measurements may underestimate the elastic modulus by up to 62% as compared to DIC measurements. Using DIC, the brushite cement was found to be much stiffer (24.3 ± 2.3 GPa) than the apatite (13.5 ± 1.6 GPa) and monetite (7.1 ± 1.0 GPa) cements, and elastic moduli were inversely related to the porosity of the materials. Poisson's ratio was determined to be 0.26 ± 0.02 for brushite, 0.21 ± 0.02 for apatite and 0.20 ± 0.03 for monetite. All investigated CPCs showed low strain-to-crack-initiation (0.17–0.19%). In summary, the elastic modulus of CPCs is substantially higher than previously reported and it is concluded that an accurate procedure is a prerequisite in order to properly compare the mechanical properties of different CPC formulations. It is recommended to use spherically seated platens and measuring the strain at a relevant resolution and on the specimen surface.

    National Category
    Ceramics Medical Materials Biomaterials Science
    Identifiers
    urn:nbn:se:uu:diva-316718 (URN)10.1016/j.jmbbm.2017.06.023 (DOI)
    Funder
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-2047Swedish Research Council, 621-2011-6258
    Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-08-03Bibliographically approved
    4. Evaluation of a porosity measurement method for wet calcium phosphate cements
    Open this publication in new window or tab >>Evaluation of a porosity measurement method for wet calcium phosphate cements
    Show others...
    2015 (English)In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 30, no 5, 526-536 p.Article in journal (Refereed) Published
    Abstract [en]

    The porosity of a calcium phosphate cement is a key parameter as it affects several important properties of the cement. However, a successful, non-destructive porosity measurement method that does not include drying has not yet been reported for calcium phosphate cements. The aim of this study was to evaluate isopropanol solvent exchange as such a method. Two different types of calcium phosphate cements were used, one basic (hydroxyapatite) and one acidic (brushite). The cements were allowed to set in an aqueous environment and then immersed in isopropanol and stored under three different conditions: at room temperature, at room temperature under vacuum (300 mbar) or at 37􏰀C. The specimen mass was monitored regularly. Solvent exchange took much longer time to reach steady state in hydroxyapatite cements compared to brushite cements, 350 and 18 h, respectively. Furthermore, the immersion affected the quasi-static compressive strength of the hydroxyapatite cements. However, the strength and phase composition of the brushite cements were not affected by isopropanol immersion, suggesting that isopropanol solvent exchange can be used for brushite calcium phosphate cements. The main advantages with this method are that it is non-destructive, fast, easy and the porosity can be evaluated while the cements remain wet, allowing for further analysis on the same specimen. 

    Place, publisher, year, edition, pages
    Sage Publications, 2015
    Keyword
    Calcium phosphate, bone cement, porosity, solvent exchange, brushite, hydroxyapatite
    National Category
    Ceramics Biomaterials Science Medical Materials
    Research subject
    Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-258636 (URN)10.1177/0885328215594293 (DOI)000367743900003 ()26163278 (PubMedID)
    Funder
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-2047Swedish Research Council, 621-2011-6258
    Available from: 2015-07-17 Created: 2015-07-17 Last updated: 2017-03-22Bibliographically approved
    5. Long-term in vitro degradation of a high-strength brushite cement in water, PBS, and serum solution
    Open this publication in new window or tab >>Long-term in vitro degradation of a high-strength brushite cement in water, PBS, and serum solution
    2015 (English)In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, 575079Article in journal (Refereed) Published
    Abstract [en]

    Bone loss and fractures may call for the use of bone substituting materials, such as calcium phosphate cements (CPCs). CPCs can be degradable, and, to determine their limitations in terms of applications, their mechanical as well as chemical properties need to be evaluated over longer periods of time, under physiological conditions. However, there is lack of data on how the in vitro degradation affects high-strength brushite CPCs over longer periods of time, that is, longer than it takes for a bone fracture to heal. This study aimed at evaluating the long-term in vitro degradation properties of a high-strength brushite CPC in three different solutions: water, phosphate buffered saline, and a serum solution. Microcomputed tomography was used to evaluate the degradation nondestructively, complemented with gravimetric analysis. The compressive strength, chemical composition, and microstructure were also evaluated. Major changes from 10 weeks onwards were seen, in terms of formation of a porous outer layer of octacalcium phosphate on the specimens with a concomitant change in phase composition, increased porosity, decrease in object volume, and mechanical properties. This study illustrates the importance of long-term evaluation of similar cement compositions to be able to predict the material’s physical changes over a relevant time frame. 

    Place, publisher, year, edition, pages
    Hindawi Publishing Corporation, 2015
    Keyword
    Calcium phosphate, brushite, bone cement, degradation, in vitro, solvent exchange, compressive strength, micro-CT, porosity
    National Category
    Ceramics Bio Materials Biomaterials Science Medical Materials
    Research subject
    Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-265319 (URN)10.1155/2015/575079 (DOI)000364660000001 ()
    Funder
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-207Swedish Research Council, 621-2011-6258
    Available from: 2015-10-27 Created: 2015-10-27 Last updated: 2017-03-22Bibliographically approved
    6. Compressive fatigue properties of an acidic calcium phosphate cement—effect of phase composition
    Open this publication in new window or tab >>Compressive fatigue properties of an acidic calcium phosphate cement—effect of phase composition
    2017 (English)In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 28, no 3, 41Article in journal (Refereed) Published
    Abstract [en]

    Calcium phosphate cements (CPCs) are synthetic bone grafting materials that can be used in fracture stabilization and to fill bone voids after, e.g., bone tumour excision. Currently there are several calcium phosphate-based formulations available, but their use is partly limited by a lack of knowledge of their mechanical properties, in particular their resistance to mechanical loading over longer periods of time. Furthermore, depending on, e.g., setting conditions, the end product of acidic CPCs may be mainly brushite or monetite, which have been found to behave differently under quasi-static loading. The objectives of this study were to evaluate the compressive fatigue properties of acidic CPCs, as well as the effect of phase composition on these properties. Hence, brushite cements stored for different lengths of time and with different amounts of monetite were investigated under quasi-static and dynamic compression. Both storage and brushite-to-monetite phase transformation was found to have a pronounced effect both on quasi-static compressive strength and fatigue performance of the cements, whereby a substantial phase transformation gave rise to a lower mechanical resistance. The brushite cements investigated in this study had the potential to survive 5 million cycles at a maximum compressive stress of 13 MPa. Given the limited amount of published data on fatigue properties of CPCs, this study provides an important insight into the compressive fatigue behaviour of such materials. 

    Keyword
    Bone cement, brushite, monetite, fatigue, mechanical properties
    National Category
    Ceramics Medical Materials Biomaterials Science
    Research subject
    Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-314237 (URN)10.1007/s10856-017-5851-5 (DOI)000394242700006 ()28144853 (PubMedID)
    Funder
    Swedish Research Council, 621-2011-6258
    Available from: 2017-02-03 Created: 2017-01-31 Last updated: 2017-04-03Bibliographically approved
    7. Compressive fatigue properties of a high-strength, degradable calcium phosphate bone cement – influence of porosity and environment
    Open this publication in new window or tab >>Compressive fatigue properties of a high-strength, degradable calcium phosphate bone cement – influence of porosity and environment
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ceramics Medical Materials Biomaterials Science
    Identifiers
    urn:nbn:se:uu:diva-316717 (URN)
    Funder
    Swedish Research Council, 621-2011-6258
    Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-03-22
  • 14.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Acciaioli, Alice
    Istituto Ortopedico Rizzoli, Laboratorio di Tecnologia Medica.
    Lionello, Giacomo
    Istituto Ortopedico Rizzoli, Laboratorio di Tecnologia Medica.
    Ginebra, Maria-Pau
    Biomaterials, Biomechanics and Tissue Engineering Group, Dept. of Materials Science and Metallurgy, Technical University of Catalonia (UPC).
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Baleani, Massimilliano
    Istituto Ortopedico Rizzoli, Laboratorio di Tecnologia Medica.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Elastic properties and strain-to-crack-initation of calcium phosphate bone cements: revelations of a high-resolution measurement technique2017In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 74, 428-437 p.Article in journal (Refereed)
    Abstract [en]

    Calcium phosphate cements (CPCs) should ideally have mechanical properties similar to those of the bone tissue the material is used to replace or repair. Usually, the compressive strength of the CPCs is reported and, more rarely, the elastic modulus. Conversely, scarce or no data are available on Poisson's ratio and strain-to-crack-initiation. This is unfortunate, as data on the elastic response is key to, e.g., numerical model accuracy. In this study, the compressive behaviour of brushite, monetite and apatite cements was fully characterised. Measurement of the surface strains was done using a digital image correlation (DIC) technique, and compared to results obtained with the commonly used built-in displacement measurement of the materials testers. The collected data showed that the use of fixed compression platens, as opposed to spherically seated ones, may in some cases underestimate the compressive strength by up to 40%. Also, the built-in measurements may underestimate the elastic modulus by up to 62% as compared to DIC measurements. Using DIC, the brushite cement was found to be much stiffer (24.3 ± 2.3 GPa) than the apatite (13.5 ± 1.6 GPa) and monetite (7.1 ± 1.0 GPa) cements, and elastic moduli were inversely related to the porosity of the materials. Poisson's ratio was determined to be 0.26 ± 0.02 for brushite, 0.21 ± 0.02 for apatite and 0.20 ± 0.03 for monetite. All investigated CPCs showed low strain-to-crack-initiation (0.17–0.19%). In summary, the elastic modulus of CPCs is substantially higher than previously reported and it is concluded that an accurate procedure is a prerequisite in order to properly compare the mechanical properties of different CPC formulations. It is recommended to use spherically seated platens and measuring the strain at a relevant resolution and on the specimen surface.

  • 15.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Acciaioli, Alice
    Lionello, Giacomo
    Ginebra, Maria-Pau
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Baleani, Massimiliano
    Compressive strength increase of calcium phosphate bone cements is accompanied by a stiffness increase2016Conference paper (Other academic)
  • 16.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Holmberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman Mägi, Caroline
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fatigue life of a brushite cement under cyclic compressive loading2017Conference paper (Refereed)
  • 17.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Holmberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The influence of porosity on the fatigue properties of brushite cement2016In: Biomaterials for tissue engineering models, 2016Conference paper (Other academic)
  • 18.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Holmberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman-Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Compressive fatigue properties of a high-strength, degradable calcium phosphate bone cement – influence of porosity and environmentManuscript (preprint) (Other academic)
  • 19.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Maazouz, Yassine
    Biomaterials, Biomechanics and Tissue Engineering Group, Dept. of Materials Science and Metallurgy, Technical University of Catalonia .
    Ginebra, Maria-Pau
    Biomaterials, Biomechanics and Tissue Engineering Group, Dept. of Materials Science and Metallurgy, Technical University of Catalonia .
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    A non-drying porosity evaluation method for calcium phosphate cements2014In: 26th Symposium and Annual Meeting of the International Society for Ceramics in Medicine, 2014, 68-68 p.Conference paper (Refereed)
  • 20.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Maazouz, Yassine
    Ginebra, Maria-Pau
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Evaluation of a porosity measurement method for wet calcium phosphate cements2015In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 30, no 5, 526-536 p.Article in journal (Refereed)
    Abstract [en]

    The porosity of a calcium phosphate cement is a key parameter as it affects several important properties of the cement. However, a successful, non-destructive porosity measurement method that does not include drying has not yet been reported for calcium phosphate cements. The aim of this study was to evaluate isopropanol solvent exchange as such a method. Two different types of calcium phosphate cements were used, one basic (hydroxyapatite) and one acidic (brushite). The cements were allowed to set in an aqueous environment and then immersed in isopropanol and stored under three different conditions: at room temperature, at room temperature under vacuum (300 mbar) or at 37􏰀C. The specimen mass was monitored regularly. Solvent exchange took much longer time to reach steady state in hydroxyapatite cements compared to brushite cements, 350 and 18 h, respectively. Furthermore, the immersion affected the quasi-static compressive strength of the hydroxyapatite cements. However, the strength and phase composition of the brushite cements were not affected by isopropanol immersion, suggesting that isopropanol solvent exchange can be used for brushite calcium phosphate cements. The main advantages with this method are that it is non-destructive, fast, easy and the porosity can be evaluated while the cements remain wet, allowing for further analysis on the same specimen. 

  • 21.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Compressive fatigue properties of a commercially available acrylic bone cement for vertebroplasty2014In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 13, no 6, 1199-1207 p.Article in journal (Refereed)
    Abstract [en]

    Acrylic bone cements are widely used for fixation of joint prostheses as well as for vertebral body augmentation procedures of vertebroplasty and balloon kyphoplasty, with the cement zone(s) being subjected to repeated mechanical loading in each of these applications. Although, in vertebroplasty and balloon kyphoplasty, the cement zone is exposed to mainly cyclical compressive load, the compressive fatigue properties of acrylic bone cements used in these procedures are yet to be determined. The purposes of the present study were to determine the compressive fatigue properties of a commercially available cement brand used in vertebroplasty, including the effect of frequency on these properties; to identify the cement failure modes under compressive cyclical load; and to introduce a screening method that may be used to shorten the lengthy character of the standardized fatigue tests. Osteopal®V was used as the model cement in this study. The combinations of maximum stress and frequency used were 50.0, 55.0, 60.0, 62.5 and 75.5 MPa at 2 Hz; and of 40.0, 55.0, 60.0, 62.5 or 75.5 MPa at 10 Hz. Through analysis of nominal strain-number of loading cycles results, three cement failure modes were identified. The estimated mean fatigue limit at 2 Hz (55.4 MPa) was significantly higher than that at 10 Hz (41.1 MPa). The estimated fatigue limit at 2 Hz is much higher than stresses commonly found in the spine and also higher than that for other acrylic bone cements tested in a full tension–compression fatigue test, which indicates that tension–compression fatigue testing may substantially underestimate the performance of cements intended for vertebroplasty. A screening method was introduced which may be used to shorten the time spent in performing compressive fatigue tests on specimens of acrylic bone cement for use in vertebral body augmentation procedures. 

  • 22.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Compressive fatigue properties of acrylic bone cement for vertebroplasty2013In: The 23rd Interdisciplinary Research Conference on Injectable Osteoarticular Biomaterials in Bone Augmentation Procedures: Proceedings, 2013Conference paper (Refereed)
  • 23.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mechanical Properties of Brushite Calcium Phosphate Cements2017In: The World Scientific Encyclopedia of Nanomedicine and Bioengineering II: Bioimplants, Regenerative Medicine, and Nano-Cancer Diagnosis and Phototherapy: Volume 3: Design of Bioactive Materials for Bone Repair and Regeneration / [ed] Shi, D., Singapore: World Scientific Pte Ltd. , 2017Chapter in book (Refereed)
  • 24.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Compressive Fatigue Properties of Acidic Calcium Phosphate Cement2014In: Proceedings of 7th World Congress of Biomechanics, 2014Conference paper (Refereed)
  • 25.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Long-term in vitro degradation of a high-strength brushite cement in water, PBS, and serum solution2015In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, 575079Article in journal (Refereed)
    Abstract [en]

    Bone loss and fractures may call for the use of bone substituting materials, such as calcium phosphate cements (CPCs). CPCs can be degradable, and, to determine their limitations in terms of applications, their mechanical as well as chemical properties need to be evaluated over longer periods of time, under physiological conditions. However, there is lack of data on how the in vitro degradation affects high-strength brushite CPCs over longer periods of time, that is, longer than it takes for a bone fracture to heal. This study aimed at evaluating the long-term in vitro degradation properties of a high-strength brushite CPC in three different solutions: water, phosphate buffered saline, and a serum solution. Microcomputed tomography was used to evaluate the degradation nondestructively, complemented with gravimetric analysis. The compressive strength, chemical composition, and microstructure were also evaluated. Major changes from 10 weeks onwards were seen, in terms of formation of a porous outer layer of octacalcium phosphate on the specimens with a concomitant change in phase composition, increased porosity, decrease in object volume, and mechanical properties. This study illustrates the importance of long-term evaluation of similar cement compositions to be able to predict the material’s physical changes over a relevant time frame. 

  • 26.
    Ajaxon, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Compressive fatigue properties of an acidic calcium phosphate cement—effect of phase composition2017In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 28, no 3, 41Article in journal (Refereed)
    Abstract [en]

    Calcium phosphate cements (CPCs) are synthetic bone grafting materials that can be used in fracture stabilization and to fill bone voids after, e.g., bone tumour excision. Currently there are several calcium phosphate-based formulations available, but their use is partly limited by a lack of knowledge of their mechanical properties, in particular their resistance to mechanical loading over longer periods of time. Furthermore, depending on, e.g., setting conditions, the end product of acidic CPCs may be mainly brushite or monetite, which have been found to behave differently under quasi-static loading. The objectives of this study were to evaluate the compressive fatigue properties of acidic CPCs, as well as the effect of phase composition on these properties. Hence, brushite cements stored for different lengths of time and with different amounts of monetite were investigated under quasi-static and dynamic compression. Both storage and brushite-to-monetite phase transformation was found to have a pronounced effect both on quasi-static compressive strength and fatigue performance of the cements, whereby a substantial phase transformation gave rise to a lower mechanical resistance. The brushite cements investigated in this study had the potential to survive 5 million cycles at a maximum compressive stress of 13 MPa. Given the limited amount of published data on fatigue properties of CPCs, this study provides an important insight into the compressive fatigue behaviour of such materials. 

  • 27.
    Akhtar, Sultan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Transmission Electron Microscopy of Graphene and Hydrated Biomaterial Nanostructures: Novel Techniques and Analysis2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Transmission Electron Microscopy (TEM) on light element materials and soft matters is problematic due to electron irradiation damage and low contrast. In this doctoral thesis techniques were developed to address some of those issues and successfully characterize these materials at high resolution. These techniques were demonstrated on graphene flakes, DNA/magnetic beads and a number of water containing biomaterials. The details of these studies are given below.

    A TEM based method was presented for thickness characterization of graphene flakes. For the thickness characterization, the dynamical theory of electron diffraction is used to obtain an analytical expression for the intensity of the transmitted electron beam as a function of thickness. From JEMS simulations (experiments) the absorption constant λ in a low symmetry orientation was found to be ~ 208 nm (225 ± 9 nm). When compared to standard techniques for thickness determination of graphene/graphite, the method has the advantage of being relatively simple, fast and requiring only the acquisition of bright-field (BF) images. Using the proposed method, it is possible to measure the thickness change due to one monolayer of graphene if the flake has uniform thickness over a larger area.

    A real-space TEM study on magnetic bead-DNA coil interaction was conducted and a statistical analysis of the number of beads attached to the DNA-coils was performed. The average number of beads per DNA coil was calculated around 6 and slightly above 2 for samples with 40 nm and 130 nm beads, respectively. These results are in good agreement with magnetic measurements. In addition, the TEM analysis supported an earlier hypothesis that 40 nm beads are preferably attached interior of the DNA-coils while 130 nm beads closer to the exterior of the coils.

    A focused ion-beam in-situ lift-out technique for hydrated biological specimens was developed for cryo-TEM. The technique was demonstrated on frozen Aspergillus niger spores which were frozen with liquid nitrogen to preserve their cellular structures. A thin lamella was prepared, lifted out and welded to a TEM grid. Once the lamella was thinned to electron transparency, the grid was cryogenically transferred to the TEM using a cryo-transfer bath. The structure of the cells was revealed by BF imaging. Also, a series of energy filtered images was acquired and C, N and Mn elemental maps were produced. Furthermore, 3 Å lattice fringes of the underlying Al support were successfully resolved by high resolution imaging, confirming that the technique has the potential to extract structural information down to the atomic scale. The experimental protocol is ready now to be employed on a large variety of samples e.g. soft/hard matter interfaces.

    List of papers
    1. A simple TEM method for fast thickness characterization of suspendedgraphene flakes
    Open this publication in new window or tab >>A simple TEM method for fast thickness characterization of suspendedgraphene flakes
    (English)Manuscript (preprint) (Other academic)
    National Category
    Nano Technology Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-171983 (URN)
    Available from: 2012-03-30 Created: 2012-03-30 Last updated: 2012-08-01
    2. Mild sonochemical exfoliation of bromine-intercalated graphite a new route towards graphene
    Open this publication in new window or tab >>Mild sonochemical exfoliation of bromine-intercalated graphite a new route towards graphene
    Show others...
    2009 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 42, no 11, 112003- p.Article in journal (Refereed) Published
    Abstract [en]

    A method to produce suspensions of graphene sheets by combining solution-based bromine intercalation and mild sonochemical exfoliation is presented. Ultrasonic treatment of graphite in water leads to the formation of suspensions of graphite flakes. The delamination is dramatically improved by intercalation of bromine into the graphite before sonication. The bromine intercalation was verified by Raman spectroscopy as well as by x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations show an almost ten times lower interlayer binding energy after introducing Br2 into the graphite. Analysis of the suspended material by transmission and scanning electron microscopy (TEM and SEM) revealed a significant content of few-layer graphene with sizes up to 30 µm, corresponding to the grain size of the starting material

    Place, publisher, year, edition, pages
    IOP Publishing Ltd, 2009
    Keyword
    Graphene
    National Category
    Physical Sciences Organic Chemistry Engineering and Technology
    Research subject
    Chemistry with specialization in Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-111654 (URN)10.1088/0022-3727/42/11/112003 (DOI)000266250300003 ()
    Available from: 2009-12-18 Created: 2009-12-18 Last updated: 2016-04-14Bibliographically approved
    3. Graphene Formation by Sonochemical Exfoliation of Bromine-intercalated Graphite.Influence of Solvent Properties on Exfoliation Yield and Deposition Outcome
    Open this publication in new window or tab >>Graphene Formation by Sonochemical Exfoliation of Bromine-intercalated Graphite.Influence of Solvent Properties on Exfoliation Yield and Deposition Outcome
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Nano Technology
    Identifiers
    urn:nbn:se:uu:diva-171988 (URN)
    Available from: 2012-03-30 Created: 2012-03-30 Last updated: 2012-09-18
    4. Real-Space Transmission Electron Microscopy Investigations of Attachment of Functionalized Magnetic Nanoparticles to DNA-Coils Acting as a Biosensor
    Open this publication in new window or tab >>Real-Space Transmission Electron Microscopy Investigations of Attachment of Functionalized Magnetic Nanoparticles to DNA-Coils Acting as a Biosensor
    Show others...
    2010 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 41, 13255-13262 p.Article in journal (Refereed) Published
    Abstract [en]

    The present work provides the first real-space analysis of nanobead-DNA coil interactions. Immobilization of oligonucleotide-functionalized magnetic nanobeads in rolling circle amplified DNA-coils was studied by complex magnetization measurements and transmission electron microscopy (TEM), and a statistical analysis of the number of beads hybridized to the DNA-coils was performed. The average number of beads per DNAcoil using the results from both methods was found to be around 6 and slightly above 2 for samples with 40 and 130 nm beads, respectively. The TEM analysis supported an earlier hypothesis that 40 nm beads are preferably immobilized in the interior of DNA-coils whereas 130 nm beads, to a larger extent, are immobilized closer to the exterior of the coils. The methodology demonstrated in the present work should open up new possibilities for characterization of interactions of a large variety of functionalized nanoparticles with macromolecules, useful for gaining more fundamental understanding of such interactions as well as for optimizing a number of biosensor applications.

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials
    Identifiers
    urn:nbn:se:uu:diva-132261 (URN)10.1021/jp105756b (DOI)000282855100028 ()
    Available from: 2010-10-18 Created: 2010-10-18 Last updated: 2016-12-01Bibliographically approved
    5. Impact of matrix properties on survival of freeze-dried bacteria
    Open this publication in new window or tab >>Impact of matrix properties on survival of freeze-dried bacteria
    Show others...
    2011 (English)In: Journal of the Science of Food and Agriculture, ISSN 0022-5142, E-ISSN 1097-0010, Vol. 91, no 14, 2518-2528 p.Article in journal (Refereed) Published
    Abstract [en]

    Background:

    Disaccharides are in general first choice as formulation compounds when freezedrying microorganisms. Although polysaccharides and other biopolymers are considered too large to stabilize and interact with cell components in the same beneficial way as disaccharides, polymers have been reported to support cell survival. In the present study we compare the efficiency of sucrose, the polymers Ficoll, hydroxyethylcellulose, hydroxypropylmethylcellulose and polyvinylalcohol to support survival of three bacterial strains during freeze-drying. The initial osmotic conditions were adjusted to be similar for all formulations. Formulation characterization was used to interpret the impact that different compound properties had on cell survival.

    Results:

    Despite differences in molecular size, both sucrose and the sucrose based polymer Ficoll supported cell survival after freeze-drying equally well. All formulations became amorphous upon dehydration. Scanning electron microscopy and X-ray diffraction data showed that the discerned differences in structure of the dry formulations had little impact on the survival rates. The capability of the polymers to support cell survival correlated with the surface activity of the polymers in a similar way for all investigated bacterial strains.

    Conclusion:

    Polymer-based formulations can support cell survival as effectively as disaccharides if formulation properties of importance for maintaining cell viability are identified and controlled.

    Keyword
    formulation, freeze-drying, biopolymer, sucrose, bacteria, surface
    National Category
    Food Science Engineering and Technology
    Research subject
    Biology with specialization in Microbiology; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-138967 (URN)10.1002/jsfa.4343 (DOI)000296385900004 ()
    Available from: 2010-12-22 Created: 2010-12-21 Last updated: 2012-08-01Bibliographically approved
    6. Direct ”Click” Synthesis of Hybrid Bisphosphonate-Hyaluronic Acid Hydrogel in Aqueous Solution for Biomineralization
    Open this publication in new window or tab >>Direct ”Click” Synthesis of Hybrid Bisphosphonate-Hyaluronic Acid Hydrogel in Aqueous Solution for Biomineralization
    Show others...
    2012 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 24, no 9, 1690-1697 p.Article in journal (Refereed) Published
    Abstract [en]

    We report the synthesis of injectable in situ forming hybrid hydrogel material and investigate its ability to support the mineralization process under mild conditions. To achieve this, we have prepared a hyaluronic acid (HA) derivative that is dually functionalized with cross-linkable hydrazide groups and bisphosphonate ligands (HA-hy-BP). The hybrid hydrogel can be formed by simple mixing of two solutions: the solution of HA-hy-BP and the Ca2+ ions containing solution of aldehyde-derivatized HA (HA-al). We found that the conjugation of BP, a P-C-P analogue of pyrophosphate, to the hydrogel matrix promotes an efficient and fast mineralization of the matrix. The mineralization is facilitated by the strong interaction between BP residues and Ca2+ ions that serve as nanometer-sized nucleation points for further calcium phosphate deposition within the HA hydrogel. Compared with previously reported hydrogel template-driven mineralization techniques, the present approach is maximally adapted for clinical settings since the formation of the hybrid takes place during quick mixing of the sterilized solutions. Moreover, the hybrid hydrogel is formed from in vivo degradable components of the extracellular matrix and therefore can be remodeled in vivo through concerted HA degradation and calcium phosphate mineralization.

    Keyword
    hybrid organic-inorganic materials, injectable materials, hydrogels, hyaluronic acid, mineralization
    National Category
    Biochemistry and Molecular Biology Materials Engineering Polymer Chemistry
    Research subject
    Engineering Science with specialization in Materials Science; Chemistry with specialization in Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-171989 (URN)10.1021/cm300298n (DOI)000303628100019 ()
    Available from: 2012-03-30 Created: 2012-03-30 Last updated: 2014-06-30Bibliographically approved
    7. A site-specific focused-ion-beam lift-out method for cryo transmission electron microscopy
    Open this publication in new window or tab >>A site-specific focused-ion-beam lift-out method for cryo transmission electron microscopy
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Structural Biology Engineering and Technology Subatomic Physics
    Identifiers
    urn:nbn:se:uu:diva-171990 (URN)
    Available from: 2012-03-30 Created: 2012-03-30 Last updated: 2012-08-01
  • 28.
    Akhtar, Sultan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Rubino, Stefano
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    A simple TEM method for fast thickness characterization of suspendedgraphene flakesManuscript (preprint) (Other academic)
  • 29.
    Alfredsson, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Varför svänger stenen?: En studie i curlingens komplexa tribosystem2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The tribo system ice-curling stone was investigated in order to understand the mechanisms behind the stones' behavior on the ice sheet. The problem with non-identical stones should also be addressed.The stone curls, that is, its sliding path deviates from a straight line to the right for a clock-wise rotation and to the left for a anti-clock-wise rotation. Several mechanisms to explain this behavior have been proposed over the years but none has been successful.By carrying out experiments at the local curling rink and studying silicon castings of ice- and stone-surfaces with scanning electron microscopy and vertical scanning interferometry, it has been decided that the curl is not due to dry friction, ice-debris or the difference in friction on the left and right side of the stone. The side force comes from the fact that the friction is higher at the back of the stone than at the front.The contact between stone and ice is never completely dry, nor in the hydrodynamic lubrication regime. It is probably a combination of hydrodynamic lubrication and a contribution from mechanical scratching of the ice. The coefficient of friction depends upon the velocity, from 0.01 for velocities around 1 m/s to higher values for lower velocities. It is not possible to make identical stones, that is identical glide band structures out of Blue Hone granite, since its composition is too inhomogeneous and its grain size is too course. It is recommended to use an amorphous or very fine grained material, at least in the surface of the glideband.

  • 30.
    Alfredsson, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nyberg, Harald
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hogmark, Sture
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribological conditions of curling - the ultimate friction sport?2011In: 18th International Conference on Wear of Materials, Philadelphia, USA, April 3-7, 2011, 2011Conference paper (Refereed)
    Abstract [en]

    Curling is an Olympic winter sport in which 8 players forming two teams slide stones across a sheet of ice towards a target area. The two teams have eight stones each and take turns to slide the stones over to the target area, some 28 m away from the release line. After being released, the stone is only affected by the sliding friction. However, this friction may be somewhat modified by sweeping the ice just in front of the sliding stone, using special curling brooms. Further, the trajectory of the stone becomes slightly curled. By slowly turning the stone clockwise when it is released, it will turn to the right, and vice versa. The best team in each round of 16 stones score one point for each stone resting closer to the target than the best stone from the opponent team.

    The game makes up a very interesting tribological system, presenting a number of challenging problems. These problems include understanding exactly:

    • what determines the level of friction, and how it is affected by the sweeping,
    • how the roughness of the stone influences the friction, and how the sliding surface should best be prepared to give a stable and repeatable friction,
    • how the intentionally bumpy "pebbled" ice structure influences the friction,
    • the size and distribution of the contact spots between the rough stone and the pebbled ice,
    • the mechanism causing the curl of the stone - "Why does the stone curl?".

    This poster is based on an experimental project, and presents this very intriguing tribological system. It offers some ready explanations and challenges the visiting tribologists to contribute their insights.

  • 31.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Eriksson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jafri, S. Hassan M.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kumar, M. S. Sharath
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ögren, Jim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    An electron energy loss spectrometer based streak camera for time resolved TEM measurements2017In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 176, 5-10 p.Article in journal (Refereed)
    Abstract [en]

    We propose an experimental setup based on a streak camera approach inside an energy filter to measure time resolved properties of materials in the transmission electron microscope (TEM). In order to put in place the streak camera, a beam sweeper was built inside an energy filter. After exciting the TEM sample, the beam is swept across the CCD camera of the filter. We describe different parts of the setup at the example of a magnetic measurement. This setup is capable to acquire time resolved diffraction patterns, electron energy loss spectra (EELS) and images with total streaking times in the range between 100 ns and 10 μs.

  • 32.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xie, Ling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    van Sebille, Martijn
    Delft University of Technology, Netherlands.
    Fusi, Adele
    Delft University of Technology, Netherlands.
    van Swaaij, Rene A C M M
    Delft University of Technology, Netherlands.
    Zeman, Miro
    Delft University of Technology, Netherlands.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    TEM analysis of multilayered nanostructures formed in the rapid thermal annealed silicon rich silicon oxide film2016In: European Microscopy Congress 2016: Proceedings, 2016, 965-966 p.Conference paper (Other academic)
    Abstract [en]

    Silicon (Si) nanoparticles (NPs) embedded in an ultrathin silicon rich silicon oxide (SRSO) film through the thermal annealing process has emerged as a highly absorbing layer for third-generation solar cells 1. The concept of using Si NPs is to achieve a band gap tunable absorber layer by controlling the size and structure of Si NPs because of the quantum confinement effect 2. In our study, a multilayer stack of silicon oxide with 35 periods of alternating layers of 1-nm thick near-stoichiometric and 3-nm thick Si-rich hydrogenated silicon oxide were deposited on fused quartz substrate by plasma-enhanced chemical vapor deposition (PECVD) method. Two samples were annealed using a rapid thermal annealing (RTA) furnace in forming gas atmosphere (90% N2 + 10% H2) for 210s and 270s respectively. From the Raman spectroscopy, a reduction in crystallinity of Si has been discovered from 210s annealed sample to 270s annealed sample (shown in Figure 2). The goal of transmission electron microscopy (TEM) analysis is to investigate the nanostructural change of Si in these two annealed samples and try to correlate the TEM observations to the Raman spectroscopy results.

    As the dimension of the Si nanostructures formed in SRSO films is in nanometer-scale, the energy-filtered TEM (EFTEM) tomography technique using the low-loss signals in electron energy-loss spectroscopy (EELS) has been applied as a powerful technique to correlate the precipitated Si nanostructures to the phase transformation mechanisms in the thermally annealed SRSO films 3. In this case, EFTEM spectrum-imaging (SI) technique was applied to characterize the Si nanostructures formed in SRSO films by different annealing times. The EFTEM SI dataset was acquired from -4eV to 40eV using a 2eV energy slit and the reconstructed zero loss peak (ZLP) was used to calibrate the spectra shift. Si plasmon images were extracted by fitting a Gaussian into the low-loss region with a peak position at 16.7 eV 4 and FWHM of 4.5 eV. In order to analyze the multilayer structures at different annealing durations, the TEM samples were prepared in cross sectional geometry using the conventional polishing and ion milling methods.

    Figure 1 shows the EFTEM images extracted from the Si plasmon peak, in these images Si appears as bright contrasts. For shorter annealing time, an alternating bright and dark contrast can be observed which indicates that the multilayer structure still remains whereas for longer annealing time, Si shows nanoparticles like contrast. The continuous layer like contrasts shown in Figure 1(a) indicates the overlapping of the contrasts generated by small Si crystallites in a very high density. After longer annealing time (Figure 1(b)), the small Si crystallites grow in size but may take overall less volume fraction due to the Ostwald ripening process. Therefore, it explains the reduction in crystallinity of Si discovered from 210s annealed sample to 270s annealed sample by Raman. However, such a reduction in Si crystallinity was not observed in nitrogen annealed SRSO films, this indicates that samples annealed in the forming gas environment follow a different crystallization mechanism and hydrogen must play a decisive role during the Si crystallization at the initial stage.

  • 33.
    Almandoz-Gil, Leire
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Geriatrics.
    Welander, Hedvig
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Geriatrics.
    Ihse, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Geriatrics.
    Emami Khoonsari, Payam
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cancer Pharmacology and Computational Medicine.
    Musunuri, Sravani
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Lendel, Christofer
    KTH, Royal Institute of Technology, Sweden.
    Sigvardson, Jessica
    BioArctic AB, Sweden.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Ingelsson, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Geriatrics.
    Kultima, Kim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cancer Pharmacology and Computational Medicine.
    Bergström, Joakim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Geriatrics.
    Low molar excess of 4-oxo-2-nonenal and 4-hydroxy-2-nonenal promote oligomerization of alpha-synuclein through different pathways2017In: Free Radical Biology & Medicine, ISSN 0891-5849, E-ISSN 1873-4596, Vol. 110, 421-431 p.Article in journal (Refereed)
  • 34.
    Altundal, Sahin
    et al.
    nstitute of Biomaterials and Biomechanics, Riga Technical University, Latvia.
    Gross, Karlis Agris
    nstitute of Biomaterials and Biomechanics, Riga Technical University, Latvia.
    Öhman Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Improving the Flexural Strength Test of Brushite Cement2015In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 631, 67-72 p.Article in journal (Refereed)
  • 35.
    Andersson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Graphene and graphene oxide as new lubricants in industrial applications2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis report evaluatesthe lubricating effect of graphene (G)and graphene oxide (GO). Thesematerials have been added, in particlecondition, in Ag-based slidingcontacts and lubricating greases. Thework focuses on the tribologicalevaluation of these materials,especially friction, wear and contactresistance analyses. The friction andwear behaviors of Ag-based contactscontaining of a wide concentrationrange of graphene and graphene oxideare tested against pure silver using atest load of 2 and 10 N at a constantspeed of 5 cm/s. It was revealed thatsmall amounts of G and GO are able tosignificantly reduce the frictioncoefficient and wear rate. Contactresistance measurements revealed thatresults similar to pure Ag can beachieved with G content up to 10vol%.Possible mechanisms, which maycontribute to this tribologicalbehavior are the Ag-C interactions andthe lubricating nature of graphene.Friction tests with G and GOcontaining lubricating greases showinconsistent results, and both greasesand corresponding test methods forevaluation require furtheroptimization. The overall, promising,tribological behavior of G and GOholds for the implementation invarious industrial applications. Thereis no doubt that these kinds ofmaterials can play an important rolein ABBs future work. This masterthesis report shows yet anotherapplication area for theseextraordinary materials.

  • 36.
    Andersson, Gabriella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björck, Matts
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lidbaum, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Chacon, Cyril
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Zlotea, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Valizadeh, Sima
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Structure of Fe-Co/Pt(001) superlattices: a realization of tetragonal Fe-Co alloys2007In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 19, no 1, 016008- p.Article in journal (Refereed)
    Abstract [en]

    The structural properties of a tetragonally distorted Fe1-xCox alloy, in the form of Fe1-xCox/Pt(001) superlattices with x = 0.64, have been investigated experimentally. The study follows recent theoretical predictions on the enhanced uniaxial magnetocrystalline anisotropy of such alloys with specific combinations of chemical composition and tetragonal distortion. The ratio between out-of-plane and in-plane lattice parameters in the Fe0.36Co0.64 layers, c/a, was found to vary between 1.18 and 1.31, depending on the thickness ratio between the alloy and the spacer. This covered the range of interest c/a = 1.20-1.25 in the previous calculations and should be compared to c/a = 1 in the original bcc alloy lattice. Simulations of x-ray diffraction patterns as well as density functional calculations support the derivation of the Fe0.36Co0.64 lattice parameters.

  • 37. Andersson, Gunnar
    et al.
    Öberg, Åke
    Grandin, Martina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Understanding field experience of contact performance from lab fretting tests of model contacts2013In: Proc. IEEE 59th HOLM Conference on Electrical Contacts, IEEE conference proceedings, 2013, 207-214 p.Conference paper (Refereed)
  • 38.
    Andersson, Per Ola
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. FOI Swedish Def Res Agcy, CBRN Def & Secur, S-90182 Umea, Sweden.; Mol Fingerprint Sweden AB, Eksatravagen 130, S-75655 Uppsala, Sweden.
    Viberg, Pernilla
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nikolajeff, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Mol Fingerprint Sweden AB, Eksatravagen 130, S-75655 Uppsala, Sweden.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Mol Fingerprint Sweden AB, Eksatravagen 130, S-75655 Uppsala, Sweden.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Mol Fingerprint Sweden AB, Eksatravagen 130, S-75655 Uppsala, Sweden.
    Nanocrystalline diamond sensor targeted for selective CRP detection: An ATR-FTIR spectroscopy study2016In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 408, no 14, 3675-3680 p.Article in journal (Refereed)
    Abstract [en]

    Protein immobilization on functionalized fluorine- terminated nanocrystalline (NCD) films was studied by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy using an immobilization protocol developed to specifically bind C-reactive protein (CRP). Using an ATR- FTIR spectroscopy method employing a force-controlled anvil-type configuration, three critical steps of the ex situ CRP immobilization were analyzed. First, the NCD surface was passivated by deposition of a copolymer layer consisting of polyethylene oxide and polypropylene oxide. Second, a synthetic modified polypeptide binder with high affinity to CRP was covalently attached to the polymeric film. Third, CRP dissolved in aqueous buffer in concentrations of 10–20 μg/ mL was added on the functionalized NCD surface. Both the amide I and II bands, due to the polypeptide binder and CRP, were clearly observed in ATR-FTIR spectra. CRP amide I bands were extracted from difference spectra and yielded bands that agreed well with the reported amide I band of free (non-bonded) CRP in solution. Thus, our results show that CRP retains its secondary structure when it is attached to the polypeptide binders. Compared to previous IR studies of CRP in solution, about 200 times lower concentration was applied in the present study. 

  • 39. Andersson, S
    et al.
    Larsson, R
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Materialvetenskap.
    Höglund, E
    HiMeC - A Swedish Programme for research and Doctoral Studies2006Conference paper (Refereed)
  • 40.
    Andre, B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hollman, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanoindentation on micro pillars for determination of intrinsic hardness and residual stress in coatings deposited on complex geometries2012In: Tribologia, ISSN 0780-2285, Vol. 31, no 1-2, 22-31 p.Article in journal (Refereed)
    Abstract [en]

    In this work a procedure to assess the local residual stress in coatings deposited on complex substrate geometries is described. A focused ion beam (FIB) is used to mill structures small enough to relax from residual stress. Nanoindentation is used to measure the change in mechanical properties, most importantly the hardness, in relaxed coating and in as-deposited coating. This change is then related to the residual stress in the coating. This relationship can then be used to calculate the residual stresses, at other positions or at other components, from changes in hardness as measured as before. The procedure is demonstrated on two different PVD coatings; one TiN coating and one nanocomposite TiNiC coating. On a large high speed steel substrate the TiN was measured to a hardness of 28 GPa using conventional techniques. Using this procedure, this could be divided into 23 GPa of intrinsic hardness and an extra 5 GPa induced by the known compressive residual stress of 3.9 GPa. When the same coating was deposited on a thin wire the full procedure allowed the residual stress to be determined to 3.5 GPa in compression.

  • 41.
    Andre, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Tribologi.
    Kassman, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Tribologi.
    Jansson, U.
    Tribology of nanocomposite materials in electrical contacts2007Conference paper (Refereed)
  • 42.
    André, Benny
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanocomposites for Use in Sliding Electrical Contacts2011Doctoral thesis, comprehensive summary (Other academic)
    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.

    List of papers
    1. Industrialisation Study of Nanocomposite nc-TiC/a-C Coatings for Electrical Contact Applications
    Open this publication in new window or tab >>Industrialisation Study of Nanocomposite nc-TiC/a-C Coatings for Electrical Contact Applications
    Show others...
    2009 (English)In: Plasma Processes and Polymers, ISSN 1612-8850, Vol. 6, no S1, S928-S934 p.Article in journal (Refereed) 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).

    Place, publisher, year, edition, pages
    WILEY-VCH Verlag GmbH & Co, 2009
    Keyword
    conductivity, inorganic materials, nanocomposites, thin films, tribology
    National Category
    Chemical Sciences Inorganic Chemistry Engineering and Technology
    Research subject
    Inorganic Chemistry; Chemistry with specialization in Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-109022 (URN)10.1002/ppap.200932303 (DOI)000272302900178 ()
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2016-04-14
    2. Synthesis, structure and properties of Ni-alloyed TiCx-based thin films
    Open this publication in new window or tab >>Synthesis, structure and properties of Ni-alloyed TiCx-based thin films
    Show others...
    2010 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 20, no 28, 5950-5960 p.Article in journal (Refereed) 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.

    National Category
    Inorganic Chemistry Engineering and Technology
    Research subject
    Chemistry with specialization in Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-109034 (URN)10.1039/c0jm00592d (DOI)000279565900025 ()
    Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2016-04-18Bibliographically approved
    3. Friction and contact resistance of nanocomposite Ti-Ni-C coatings
    Open this publication in new window or tab >>Friction and contact resistance of nanocomposite Ti-Ni-C coatings
    2011 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, no 9-10, 555-566 p.Article in journal (Refereed) 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.

    Keyword
    TiC, TiNiC, Friction, Tribofilm, Electrical contacts, Contact resistance
    National Category
    Inorganic Chemistry Engineering and Technology
    Research subject
    Inorganic Chemistry; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-109425 (URN)10.1016/j.wear.2010.12.006 (DOI)000290132500001 ()
    Available from: 2009-10-15 Created: 2009-10-15 Last updated: 2016-04-19
    4. Nanoindentation on micro pillars for determination of intrincic hardness and residual stress in coatings deposited on complex geometries
    Open this publication in new window or tab >>Nanoindentation on micro pillars for determination of intrincic hardness and residual stress in coatings deposited on complex geometries
    (English)Manuscript (preprint) (Other academic)
    Keyword
    nanoindentation, hardness, residual stress, focused ion beam, coating, PVD
    National Category
    Materials Engineering Other Materials Engineering
    Research subject
    Materials Science; Engineering Science with specialization in Tribo Materials; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-160807 (URN)
    Available from: 2011-10-31 Created: 2011-10-31 Last updated: 2016-04-22
    5. Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles
    Open this publication in new window or tab >>Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles
    2012 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 8-9, 2325-2329 p.Article in journal (Refereed) 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.

    Keyword
    Friction, Wear, Tungsten disulphide, Nanoparticles, Fullerene, Tribofilm
    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Tribo Materials; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-160806 (URN)10.1016/j.surfcoat.2011.10.012 (DOI)000300458500038 ()
    Available from: 2011-10-31 Created: 2011-10-31 Last updated: 2016-04-20
    6. Enhancing silver through embedding of fullerene like WS2 for sliding electrical contacts
    Open this publication in new window or tab >>Enhancing silver through embedding of fullerene like WS2 for sliding electrical contacts
    (English)Manuscript (preprint) (Other academic)
    Keyword
    friction, wear, electrical, contacts, tungsten, disulfide, silver
    National Category
    Materials Engineering Composite Science and Engineering Other Materials Engineering
    Research subject
    Materials Science; Engineering Science with specialization in Materials Science; Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-160808 (URN)
    Available from: 2011-11-01 Created: 2011-11-01 Last updated: 2012-05-08
  • 43.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gustavsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Svahn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles2012In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 8-9, 2325-2329 p.Article in journal (Refereed)
    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.

  • 44.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gustavsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Svahn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles2009Conference paper (Refereed)
    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.

  • 45.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gustavsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Svahn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Potential of a new low-friction coating based on inorganic fullerens: comparison with state-of-the-art PVD coatings2009Conference paper (Refereed)
  • 46.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hollman, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanoindentation on micro pillars for determination of intrincic hardness and residual stress in coatings deposited on complex geometriesManuscript (preprint) (Other academic)
  • 47.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Comparisons between commercial low-friction coatings and emerging coating concepts in ball-on-disc tests – coefficient of friction, tribofilm formation and surface damage2008Conference paper (Refereed)
  • 48.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman-Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Enhancing silver through embedding of fullerene like WS2 for sliding electrical contactsManuscript (preprint) (Other academic)
  • 49.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction and contact resistance of nanocomposite Ti-Ni-C coatings2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, no 9-10, 555-566 p.Article in journal (Refereed)
    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.

  • 50.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Lindquist, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribological testing of ceramic coatings boosted for low friction and for use in electrical contacts2008Conference paper (Refereed)
1234567 1 - 50 of 1009
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf