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  • 1.
    Aijaz, Asim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ferreira, Fabio
    Univ Coimbra, SEG CEMMPRE Dept Mech Engn, Rua Luis Reis Santos, P-3030788 Coimbra, Portugal.
    Oliveira, Joao
    Univ Coimbra, SEG CEMMPRE Dept Mech Engn, Rua Luis Reis Santos, P-3030788 Coimbra, Portugal.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Mechanical Properties of Hydrogen Free Diamond-Like Carbon Thin Films Deposited by High Power Impulse Magnetron Sputtering with Ne2018In: Coatings, ISSN 2079-6412, Vol. 8, no 11, article id 385Article in journal (Refereed)
    Abstract [en]

    Hydrogen-free diamond-like carbon (DLC) thin films are attractive for a wide range of industrial applications. One of the challenges related to the use of hard DLC lies in the high intrinsic compressive stresses that limit the film adhesion. Here, we report on the mechanical and tribological properties of DLC films deposited by High Power Impulse Magnetron Sputtering (HiPIMS) with Ne as the process gas. In contrast to standard magnetron sputtering as well as standard Ar-based HiPIMS process, the Ne-HiPIMS lead to dense DLC films with increased mass density (up to 2.65 g/cm(3)) and a hardness of 23 GPa when deposited on steel with a Cr + CrN adhesion interlayer. Tribological testing by the pin-on-disk method revealed a friction coefficient of 0.22 against steel and a wear rate of 2 x 10(-17) m(3)/Nm. The wear rate is about an order of magnitude lower than that of the films deposited using Ar. The differences in the film properties are attributed to an enhanced C ionization in the Ne-HiPIMS discharge.

  • 2.
    Andersson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Mårtensson, Gustaf
    EMSL, MC2, Chalmers University of Technology, Göteborg, Sweden.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Flowing and pressurizing a solid-liquid two phase monodispersed fluid with high solid content in a transparent microfluidic high-pressure chip2017Conference paper (Refereed)
  • 3.
    Bamford, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tool wear in turning of titanium alloy Ti–6Al–4V: Challenges and potential solutions for crater wear, diffusion and chip formation2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Titanium alloys are major materials used in the airplane industry, and prospects show that airplane production will double in the next 20 years. Consequently, the demand for cutting tools for machining of titanium alloys will increase. The primary problem when machining titanium alloys is their low thermal conductivity. Crater wear is the main factor limiting tool life, and is generally caused by thermal diffusion due to high temperatures in the tool-chip interface.

    This master’s thesis was performed in collaboration with Sandvik Coromant, with the prospect to increase knowledge of how diffusion and chip formation influences crater wear progression. The aim was to study tool wear of cutting tools when turning Ti–6Al–4V. This was done by testing two different rake face geometries, both coated and uncoated, at cutting speeds of 30–115 m/min. Diffusion was investigated to learn about the impact it has on crater wear. Chips were examined to investigate chip formation and shear strain.

    The coated modified rake face insert showed less crater wear only for the initial few seconds of machining. Uncoated inserts with a modified rake face showed higher diffusion rate and faster crater wear progression than did standard inserts. The standard inserts showed twice as long tool life as did the modified inserts. No significant differences in the chip formation mechanism were found between modified and standard inserts. Cracks were found within shear bands that were thinner than usual, which suggest that the generation of cracks allows less shear deformation.

  • 4.
    Barankova, Hana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bardos, Ladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bárdos, Adela
    Reactive Deposition by Magnetron with Magnetized Hollow Cathode Enhanced Target2018Conference paper (Refereed)
  • 5.
    Barankova, Hana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bardos, Ladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Silins, Kaspars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Amorphous Carbon Films on Glass Prepared by Hollow Cathodes at Moderate Pressure2016In: ECS Journal of Solid State Science and Technology, ISSN 2162-8769, E-ISSN 2162-8777, Vol. 5, no 9, p. N57-N60Article in journal (Refereed)
  • 6.
    Barankova, Hana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. BB Plasma Design AB, Uppsala, Sweden.
    Bardos, Ladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. BB Plasma Design AB, Uppsala, Sweden.
    Silins, Kaspars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bardos, A.
    BB Plasma Design AB.
    Reactive Deposition of TiN Films by Magnetron with Magnetized Hollow Cathode Enhanced Target2018In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 152, p. 123-127Article in journal (Refereed)
    Abstract [en]

    Magnetized Hollow Cathode Activated Magnetron in which the target is coupled with the hollow cathode magnetized by the magnetic field of the magnetron was tested in the reactive process of TiN deposition. Increased deposition rate compared to the Ti metal deposition rate was confirmed. The depositions as well as optical measurements were performed at several pressures in the reactor. The results of the TiN reactive deposition are presented and discussed, including the TiN deposition in pure nitrogen.

  • 7.
    Baránková, Hana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bardos, Ladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Silins, Kaspars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    DLC coatings prepared by hollow cathodes at moderate pressure2015Conference paper (Other academic)
    Abstract [en]

    DLC coatings were prepared using the rf powered cylindrical and linear hollow cathodes. The deposition process is hybrid, combining both the PE CVD and PVD. A cylindrical graphite nozzle and graphite plates were used as targets. The gas mixture used in the deposition process was argon with acetylene.

     

    Compared to e.g. magnetron sputtering, the optimum content of acetylene is lower. The effect of the acetylene content in the gas mixture as well as rf power on the deposition rate and properties of the coatings are evaluated.

     

    The geometrical effect is studied, the cylindrical hollow cathode and the linear hollow cathode are compared and the transfer of the optimized process from the cylindrical into the linear hollow cathode is discussed.

  • 8.
    Baránková, Hana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bardos, Ladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Silins, Silins
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    DLC coatings prepared by hollow cathodes at moderate pressure2015Conference paper (Other academic)
    Abstract [en]

    DLC coatings were prepared using the rf powered cylindrical and linear hollow cathodes. The deposition process is hybrid, combining both the PE CVD and PVD. A cylindrical graphite nozzle and graphite plates were used as targets. The gas mixture used in the deposition process was argon with acetylene.

     

    Compared to e.g. magnetron sputtering, the optimum content of acetylene is lower. The effect of the acetylene content in the gas mixture as well as rf power on the deposition rate and properties of the coatings are evaluated.

     

    The geometrical effect is studied, the cylindrical hollow cathode and the linear hollow cathode are compared and the transfer of the optimized process from the cylindrical into the linear hollow cathode is discussed.

  • 9.
    Bojestig, Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion of CVD coatings on new cemeted carbides2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

  • 10.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Biofilm elimination and detachment using photocatalytic TiO2 surfaces2011In: Conference, 2011Conference paper (Refereed)
  • 11.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Biofilm susceptibility to photocatalytic dental mateirals2011In: Conference, 2011Conference paper (Refereed)
  • 12.
    Chang, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Shah, Ali
    Aalto University.
    Zhou, Quan
    Aalto University.
    Ras, Robin
    Aalto University.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Self-transport and self-alignment of microchips using microscopic rain2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 14966Article in journal (Refereed)
    Abstract [en]

    Alignment of microchips with receptors is an important process step in the construction of integrated micro- and nanosystems for emerging technologies, and facilitating alignment by spontaneous self-assembly processes is highly desired. Previously, capillary self-alignment of microchips driven by surface tension effects on patterned surfaces has been reported, where it was essential for microchips to have sufficient overlap with receptor sites. Here we demonstrate for the first time capillary self-transport and self-alignment of microchips, where microchips are initially placed outside the corresponding receptor sites and can be self-transported by capillary force to the receptor sites followed by self-alignment. The surface consists of hydrophilic silicon receptor sites surrounded by superhydrophobic black silicon. Rain-induced microscopic droplets are used to form the meniscus for the self-transport and self-alignment. The boundary conditions for the self-transport have been explored by modeling and confirmed experimentally. The maximum permitted gap between a microchip and a receptor site is determined by the volume of the liquid and by the wetting contrast between receptor site and substrate. Microscopic rain applied on hydrophilic-superhydrophobic patterned surfaces greatly improves the capability, reliability and error-tolerance of the process, avoiding the need for accurate initial placement of microchips, and thereby greatly simplifying the alignment process.

  • 13.
    Chang, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Aalto Univ, Sch Sci, Dept Appl Phys, FI-00076 Aalto, Finland.
    Zhou, Quan
    Aalto Univ, Dept Elect Engn & Automat, FI-00076 Aalto, Finland.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    Ras, Robin
    Aalto Univ, Sch Sci, Dept Appl Phys, FI-00076 Aalto, Finland.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Capillary Self-Alignment of Microchips on Soft Substrates2016In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Vol. 7, no 3, article id 41Article in journal (Refereed)
    Abstract [en]

    Soft micro devices and stretchable electronics have attracted great interest for their potential applications in sensory skins and wearable bio-integrated devices. One of the most important steps in building printed circuits is the alignment of assembled micro objects. Previously, the capillary self-alignment of microchips driven by surface tension effects has been shown to be able to achieve high-throughput and high-precision in the integration of micro parts on rigid hydrophilic/superhydrophobic patterned surfaces. In this paper, the self-alignment of microchips on a patterned soft and stretchable substrate, which consists of hydrophilic pads surrounded by a superhydrophobic polydimethylsiloxane (PDMS) background, is demonstrated for the first time. A simple process has been developed for making superhydrophobic soft surface by replicating nanostructures of black silicon onto a PDMS surface. Different kinds of PDMS have been investigated, and the parameters for fabricating superhydrophobic PDMS have been optimized. A self-alignment strategy has been proposed that can result in reliable self-alignment on a soft PDMS substrate. Our results show that capillary self-alignment has great potential for building soft printed circuits.

  • 14.
    Chu, Jiangtao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microdialysis Sampling of Macro Molecules: Fluid Characteristics, Extraction Efficiency and Enhanced Performance2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, fluid characteristics and sampling efficiency of high molecular weight cut-off microdialysis are presented, with the aim of improving the understanding of microdialysis sampling mechanisms and its performance regarding extraction efficiency of biological fluid and biomarkers.

    Microdialysis is a well-established clinical sampling tool for monitoring small biomarkers such as lactate and glucose. In recent years, interest has raised in using high molecular weight cut-off microdialysis to sample macro molecules such as neuropeptides, cytokines and proteins. However, with the increase of the membrane pore size, high molecular weight cut-off microdialysis exhibits drawbacks such like unstable catheter performance, imbalanced fluid recovery, low and unstable molecule extraction efficiency, etc. But still, the fluid characteristics of high molecular weight cut-off microdialysis is rarely studied, and the clinical or in vitro molecule sampling efficiency from recent studies vary from each other and are difficult to compare.  

    Therefore, in this thesis three aspects of high molecular weight cut-off microdialysis have been explored. The first, the fluid characteristics of large pore microdialysis has been investigated, theoretically and experimentally. The results suggest that the experimental fluid recovery is in consistency with its theoretical formula. The second, the macromolecule transport behaviour has been visualized and semi-quantified, using an in vitro test system and fluorescence imaging. The third, two in vitro tests have been done to mimic in vivo cerebrospinal fluid sampling under pressurization, using native and differently surface modified catheters. As results, individual protein/peptide extraction efficiencies were achieved, using targeted mass spectrometry analysis.

    In summary, a theory system of the fluid characteristics of high molecular weight cut-off microdialysis has been built and testified; Macromolecular transport of microdialysis catheter has been visualized; In vivo biomolecules sampling has been simulated by well-defined in vitro studies; Individual biomolecular extraction efficiency has been shown; Different surface modifications of microdialysis catheter have been investigated. It was found that, improved sampling performance can be achieved, in terms of balanced fluid recovery and controlled protein extraction efficiency.

    List of papers
    1. Impact of static pressure on transmembrane fluid exchange in high molecular weight cut off microdialysis
    Open this publication in new window or tab >>Impact of static pressure on transmembrane fluid exchange in high molecular weight cut off microdialysis
    2014 (English)In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 16, no 2, p. 301-310Article in journal (Refereed) Published
    Abstract [en]

    With the interest of studying larger biomolecules by microdialysis (MD), this sampling technique has reached into the ultrafiltration region of fluid exchange, where fluid recovery (FR)  has a strong dependence on pressure. Hence in this study, we focus on the fluid exchange across the high molecular weight cut off MD membrane under the influence of the static pressure in the sampling environment. A theoretical model is presented for MD with such membranes, where FR has a linear dependence upon the static pressure of the sample. Transmembrane (TM) osmotic pressure difference and MD perfusion rate decide how fast FR increases with increased static pressure.

    A test chamber for in vitro MD under static pressure was constructed and validated. It can hold four MD probes under controlled pressurized conditions. Comparison showed good agreement between experiment and theory. Moreover, test results showed that the fluid recovery of the test chamber MD can be set accurately via the chamber pressure, which is controlled by sample injection into the chamber at precise rate. This in vitro system is designed for modelling in vivo MD in cerebrospinal fluid and studies with biological samples in this system may be good models for in vivo MD. 

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-212726 (URN)10.1007/s10544-013-9833-1 (DOI)000334362000013 ()
    Funder
    Swedish Research Council, P29797-1
    Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-06Bibliographically approved
    2. Fluorescence imaging of macromolecule transport in high molecular weight cut-off microdialysis
    Open this publication in new window or tab >>Fluorescence imaging of macromolecule transport in high molecular weight cut-off microdialysis
    2014 (English)In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 406, no 29, p. 7601-7609Article in journal (Refereed) Published
    Abstract [en]

    When microdialysis (MD) membrane exceeds molecular weight cut-off (MWCO) of 100 kDa, the fluid mechanics are in the ultrafiltration regime. Consequently, fluidic mass transport of macromolecules in the perfusate over the membrane may reduce the biological relevance of the sampling and cause an inflammatory response in the test subject. Therefore, a method to investigate the molecular transport of high MWCO MD is presented. An in vitro test chamber was fabricated to facilitate the fluorescent imaging of the MD sampling process, using fluoresceinylisothiocyanate (FITC) dextran and fluorescence microscopy. Qualitative studies on dextran behavior inside and outside the membrane were performed. Semiquantitative results showed clear dextran leakage from both 40 and 250 kDa dextran when 100 kDa MWCO membranes were used. Dextran 40 kDa leaked out with an order of magnitude higher concentration and the leakage pattern resembled more of a convective flow pattern compared with dextran 250 kDa, where the leakage pattern was more diffusion based. No leakage was observed when dextran 500 kDa was used as a colloid osmotic agent. The results in this study suggest that fluorescence imaging could be used as a method for qualitative and semiquantitative molecular transport and fluid dynamics studies of MD membranes and other hollow fiber catheter membranes.

    National Category
    Other Medical Engineering Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-239233 (URN)10.1007/s00216-014-8192-y (DOI)000344860300019 ()25286875 (PubMedID)
    Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-12-05Bibliographically approved
    3. Influence of surface modification and static pressure on microdialysis protein extraction efficiency
    Open this publication in new window or tab >>Influence of surface modification and static pressure on microdialysis protein extraction efficiency
    Show others...
    2015 (English)In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 17, no 5, article id UNSP 96Article in journal (Refereed) Published
    Abstract [en]

    There is growing interest in using microdialysis (MD) for monitoring larger and more complexmolecules such as neuropeptides and proteins. This promotes the use of MD membranes withmolecular weight cut off (MWCO) of 100 kDa or above. The hydrodynamic property of themembrane goes to ultrafiltration or beyond, making the MD catheters more sensitive to pressure.In the meantime, despite the large pore size, studies have shown that membrane biofouling stilllead to unstable catheter performance. The objective is to study in vitro how 500 kDa dextranand Poloxamer 407 surface modification affect the fluid recovery (FR) and extraction efficiency(EE) of 100 kDa MWCO MD catheters. A pressure chamber was designed to facilitate the tests,using as MD sample a protein standard with similar concentrations as in human cerebral spinalfluid, comparing native and Poloxamer 407 modified MD catheters. The collected dialysatefractions were examined for FR and protein EE, employing Dot-it Spot-it Protein Assay for totalprotein EE and targeted mass spectrometry (MS) for EE of individual proteins and peptides. TheFR results suggested that the surface modified catheters were less sensitive to the pressure andprovide higher precision, and provided a FR closer to 100%. The surface modification did notshow a significant effect on the protein EE. The average total protein EE of surface modifiedcatheters was slightly higher than that of the native ones. The MS EE data of individual proteinsshowed a clear trend of complex response in EE with pressure.

    Place, publisher, year, edition, pages
    Springer: , 2015
    Keywords
    microdialysis, surface modification, poloxamer, protein, extraction efficiency
    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-261031 (URN)10.1007/s10544-015-0005-3 (DOI)000362281200013 ()26342494 (PubMedID)
    Funder
    Berzelii Centre EXSELENTSwedish Research Council, P29797-1Åke Wiberg FoundationMagnus Bergvall FoundationScience for Life Laboratory - a national resource center for high-throughput molecular bioscience
    Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2017-12-04Bibliographically approved
    4. Influence of different pluronic surface modifications and pressure on microdialysis protein extraction efficiency
    Open this publication in new window or tab >>Influence of different pluronic surface modifications and pressure on microdialysis protein extraction efficiency
    Show others...
    2015 (English)In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781Article in journal (Refereed) Submitted
    Abstract [en]

    There is growing interest in using microdialysis (MD) for monitoring larger and more complexmolecules such as neuropeptides and proteins. This promotes the use of MD membranes withmolecular weight cut off (MWCO) of 100 kDa. Hence, the hydrodynamic property of themembrane goes to ultrafiltration, making the sampling more sensitive to pressure changes. Also,despite the large membrane pore size, studies have shown that membrane biofouling still leads tounstable catheter performance. Our objective is to study in vitro how four kinds of surfacemodifications (Pluronic L31, L44, F87 and F127+L31) affect the fluid recovery (FR) andextraction efficiency (EE) of 100 kDa MWCO MD catheters, under controlled pressure. Apressure chamber was employed to facilitate the tests, using as MD sample a protein standardwith proteins of similar concentrations as in human cerebral spinal fluid. The collected dialysatefractions were examined for FR and EE. Targeted mass spectrometry analysed the EE ofindividual proteins and peptides. The thicker the pluronic adsorption layer, the less thehydrodynamic diameter of the membrane pores, leading to lower and more stable FR. The foursurface modifications had three different behaviours: Pluronic F127 + L31 showed similarbehavior to the Pluronic F127 and the native original membrane; Pluronic F87 showed acontinuous EE increase with pressure; Pluronic L31 and L44 showed similar EE values, whichwere stable with pressure. Different surface modifications are clearly selective to differentproteins and peptides. We conclude that a pluronic surface modification could provide MDsampling with more stable FR, and more stable or enhanced EE with high FR, depending on theobjective of the sampling.

    Place, publisher, year, edition, pages
    Springer: , 2015
    Keywords
    microdialysis, surface modification, poloxamer, protein, extraction efficiency
    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-261557 (URN)
    Funder
    Berzelii Centre EXSELENT
    Available from: 2015-09-01 Created: 2015-09-01 Last updated: 2017-12-04Bibliographically approved
    5. Protein Desalination Chip for Mass Spectrometry Sample Preparation
    Open this publication in new window or tab >>Protein Desalination Chip for Mass Spectrometry Sample Preparation
    Show others...
    2015 (English)Conference paper, Oral presentation with published abstract (Refereed)
    Abstract [en]

    This work focuses on desalination of a protein sample in a lab-on-chip device using the ion concentration polarization (ICP) technique. It was demonstrated with a salt containing buffer with four proteins and two peptides of concentrations typical to cerebrospinal fluid (CSF). Not only was the output desalinated but its protein concentration with large molecular weight (MW) was as much as 3 times higher for the largest protein compared to the original. We conclude that ICP based microfluidic chips have great potential for desalination and protein concentration in microdialysis sampling coupled to mass spectroscopy (MS).

    Place, publisher, year, edition, pages
    MicroTAS: , 2015
    Keywords
    Ion concentration polarization, Desalination, Protein, Mass spectroscopy
    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-261067 (URN)
    Conference
    The 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2015. October 25-29, 2015. Gyeongju, Korea.
    Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2016-01-05
    6. Refined microdialysis method for protein biomarker sampling in acute brain injury in the neurointensive care setting
    Open this publication in new window or tab >>Refined microdialysis method for protein biomarker sampling in acute brain injury in the neurointensive care setting
    Show others...
    2014 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 86, no 17, p. 8671-8679Article in journal (Refereed) Published
    Abstract [en]

    There is growing interest in cerebral microdialysis (MD) for sampling of protein biomarkers in neurointensive care (NIC) patients. Published data point to inherent problems with this methodology including protein interaction and biofouling leading to unstable catheter performance. This study tested the in vivo performance of a refined MD method including catheter surface modification, for protein biomarker sampling in a clinically relevant porcine brain injury model. Seven pigs of both sexes (10-12 weeks old; 22.2-27.3 kg) were included. Mean arterial blood pressure, heart rate, intracranial pressure (ICP) and cerebral perfusion pressure was recorded during the stepwise elevation of intracranial pressure by inflation of an epidural balloon catheter with saline (1 mL/20 min) until brain death. One naïve MD catheter and one surface modified with Pluronic F-127 (10 mm membrane, 100 kDa molecular weight cutoff MD catheter) were inserted into the right frontal cortex and perfused with mock CSF with 3% Dextran 500 at a flow rate of 1.0 μL/min and 20 min sample collection. Naïve catheters showed unstable fluid recovery, sensitive to ICP changes, which was significantly stabilized by surface modification. Three of seven naïve catheters failed to deliver a stable fluid recovery. MD levels of glucose, lactate, pyruvate, glutamate, glycerol and urea measured enzymatically showed an expected gradual ischemic and cellular distress response to the intervention without differences between naïve and surface modified catheters. The 17 most common proteins quantified by iTRAQ and nanoflow LC-MS/MS were used as biomarker models. These proteins showed a significantly more homogeneous response to the ICP intervention in surface modified compared to naïve MD catheters with improved extraction efficiency for most of the proteins. The refined MD method appears to improve the accuracy and precision of protein biomarker sampling in the NIC setting.

    National Category
    Analytical Chemistry Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-232026 (URN)10.1021/ac501880u (DOI)000341229200025 ()25075428 (PubMedID)
    Available from: 2014-09-12 Created: 2014-09-12 Last updated: 2017-12-05Bibliographically approved
    7. Cerebral microdialysis for protein biomarker monitoring in the neurointensive care setting - a technical approach
    Open this publication in new window or tab >>Cerebral microdialysis for protein biomarker monitoring in the neurointensive care setting - a technical approach
    Show others...
    2014 (English)In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 5, p. 245-Article in journal (Refereed) Published
    Abstract [en]

    Cerebral microdialysis (MD) was introduced as a neurochemical monitoring method in the early 1990s and is currently widely used for the sampling of low molecular weight molecules, signaling energy crisis, and cellular distress in the neurointensive care (NIC) setting. There is a growing interest in MD for harvesting of intracerebral protein biomarkers of secondary injury mechanisms in acute traumatic and neurovascular brain injury in the NIC community. The initial enthusiasm over the opportunity to sample protein biomarkers with high molecular weight cut-off MD catheters has dampened somewhat with the emerging realization of inherent methodological problems including protein-protein interaction, protein adhesion, and biofouling, causing an unstable in vivo performance (i.e., fluid recovery and extraction efficiency) of the MD catheter. This review will focus on the results of a multidisciplinary collaborative effort, within the Uppsala Berzelii Centre for Neurodiagnostics during the past several years, to study the features of the complex process of high molecular weight cut-off MD for protein biomarkers. This research has led to new methodology showing robust in vivo performance with optimized fluid recovery and improved extraction efficiency, allowing for more accurate biomarker monitoring. In combination with evolving analytical methodology allowing for multiplex biomarker analysis in ultra-small MD samples, a new opportunity opens up for high-resolution temporal mapping of secondary injury cascades, such as neuroinflammation and other cell injury reactions directly in the injured human brain. Such data may provide an important basis for improved characterization of complex injuries, e.g., traumatic and neurovascular brain injury, and help in defining targets and treatment windows for neuroprotective drug development.

    National Category
    Neurology Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-239227 (URN)10.3389/fneur.2014.00245 (DOI)25520696 (PubMedID)
    Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-12-05Bibliographically approved
  • 15.
    Dalbauer, V
    et al.
    TU Wien, Christian Doppler Lab Applicat Oriented Coating D, Inst Mat Sci & Technol, Vienna, Austria.
    Ramm, J.
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein.
    Kolozsvari, S.
    Plansee Composite Mat GmbH, Lechbruck Am See, Germany.
    Paneta, Valentina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Koller, C. M.
    TU Wien, Christian Doppler Lab Applicat Oriented Coating D, Inst Mat Sci & Technol, Vienna, Austria;TU Wien, Inst Mat Sci & Technol, Vienna, Austria.
    Mayrhofer, P. H.
    TU Wien, Christian Doppler Lab Applicat Oriented Coating D, Inst Mat Sci & Technol, Vienna, Austria;TU Wien, Inst Mat Sci & Technol, Vienna, Austria.
    On the phase formation of cathodic arc evaporated Al1-xCrx-based intermetallic coatings and substoichiometric oxides2018In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 352, p. 392-398Article in journal (Refereed)
    Abstract [en]

    The phase evolution of Al1-xCrx-based intermetallic coatings and corresponding substoichiometric oxides grown by cathodic arc evaporation was investigated in order to obtain a better understanding of the relation between oxygen flow rate, Al and Cr content, and structural evolution of the coatings deposited. When using 20 sccm Ar, or 50 sccm O-2, or 100 sccm O-2 per active source (p.a.s.) the cathode reaction zone consists of various intermetallic Al-Cr-compounds, which are in good agreement with the binary Al-Cr phase diagram. This is generally also reflected in the phase composition of the metallic and substoichiometric oxide coatings. The Al-rich compositions, Al0.75Cr0.25 and Al0.70Cr0.30, show a strong tendency for the formation of gamma(1)-Al8Cr5 phases. Mostly, the coating compositions of the metallic constituents of the synthesised intermetallic and substoichiometric oxide coatings deviate from the elemental compositions of the cathode, show enrichment in Cr. This deviation is more pronounced for Cr-rich cathodes using low O-2 flow rates during deposition. The dense columnar structure of the intermetallic coatings (hardness values between 2.5 and 10.2 GPa) turns into a nano-composite-like morphology for depositions with 50 and 100 sccm O-2 p.a.s., which in turn leads to a significant hardness increase up to similar to 24 GPa. Among all coatings investigated, the Cr-rich compositions have higher hardness and denser morphology than the Al-rich layers.

  • 16.
    Edin, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kaplan, Bartek
    Sandvik Coromant R&D, Stockholm, Sweden.
    Blomqvist, Andreas
    Sandvik Coromant R&D, Stockholm, Sweden.
    First principles study of C diffusion in WC/W interfaces observed in WC/Co tools after Ti-alloy machining2019In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 161, p. 236-243Article in journal (Refereed)
    Abstract [en]

    Ti-alloys have many qualities making them ideal for use in aerospace applications, medical implants and chemical industries such as high strength to weight ratio, good high temperature strength and chemical stability. One downside to Ti-alloys is, however, that they are considered difficult to machine. Several investigations have been made in order to understand the wear mechanisms present in machining of Ti-alloys and the most common understanding is a combination of attrition and dissolution-diffusion. Observations by Odelros et al. [1] have shown that there exists a small layer of pure bcc W on top of the outermost WC grains after turning of Ti-6Al-4V. In order for such a layer to form C has to diffuse away from the WC leaving behind only W. In this work Density Functional Theory (DFT) is used together with Harmonic Transition State Theory (HTST) to investigate the prefactors and barriers for C diffusion into and within two different WC/W interfaces, [0001]/[111] and [10 (1) over bar0]/[100]. The diffusion into the interfaces show that the barrier for the [0001]/[111] interface is more than twice as high as the barrier for the [10 (1) over bar0]/[100] interface. Diffusion within the interfaces show, on average, slightly higher barriers for the [0001]/[111] interface.

  • 17.
    Edqvist, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Snis, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Casanova Mohr, Raimon
    SiC, Electronics Department, University of Barcelona, Barcelona, Spain.
    Scholz, Oliver
    IBMT, Fraunhofer Institute for Biomedical Engineering, St Ingbert, Germany.
    Corradi, Paolo
    Scuola Superiore Sant’Anna, Pisa, Italy.
    Gao, Jianbo
    IBMT, Fraunhofer Institute for Biomedical Engineering, St Ingbert, Germany.
    Di´eguez, Angel
    SiC, Electronics Department, University of Barcelona, Barcelona, Spain.
    Wyrsch, Nicolas
    Institut de Microtechnique, University of Neuchˆatel, Neuchˆatel, Switzerland.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Evaluation of building technology for mass producible millimetre-sized robots using flexible printed circuit boards2009In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 19, no 7, p. 11pp-Article in journal (Refereed)
    Abstract [en]

    Initial tests of a building technology for a compact three-dimensional mass produciblemicrorobot are presented. The 3.9 × 3.9 × 3.3 mm3 sized prototype robot represents amicrosystem with actuators, sensors, energy management and integrated electronics. Theweight of a folded robot is 65 mg and the total volume is less than 23 mm3. The design of theinterfaces of the different modules in the robot, as well as the building technology, isdescribed. The modules are assembled using conductive adhesive with industrial surfacemounting technology on a thin double-sided flexible printed circuit board. The final shape ofthe microrobots is achieved by folding the flexible printed circuit board twice. Electrical andmechanical studies are performed to evaluate the assembly and it is concluded that thetechnology can be used for this type of microsystem. Several issues using the presentedassembly technique are identified and addressed.

  • 18.
    Eriksson, Jenny
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Galling of high strength steels and stainless steels in sheet metal forming as evaluated using pin-on-disc testing2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis focuses on the problem galling in sheet metal forming operations. Galling occurs when sheet metal transfers from the sheet surface onto the tool surface and causes surface damages to following sheets in the forming operation. When this happens the tool must be replaced causing production stops and additional expenses.

    The increasing use of high strength steel grades combined with the desire to use more environmentally friendly or no lubricants exposes the tools used for sheet metal forming for tougher forming conditions with higher contact pressures and thus an increasing risk for material pick-up and galling. To prevent this new tool steels, lubricants and coatings have been developed. In this thesis a number of tool steels, high strength steels, stainless steels, coatings and lubricants have been investigated with the test method pin-on-disc testing in order to explain how different premises, such as chemical composition, mechanical properties and surface topography influence on the galling tendency in sheet metal forming.

    The results show that there is a big difference in performance between a conventional cast tool steel and a powder metallurgy tool steel with respect to the galling tendency. The results also show that the surface topography of both the tool steels and the sheet materials influence on the performance of the lubricants and the galling tendency.   

    When coating a tool steel, the substrate hardness is of greatest importance for the performance and wear of the coating. For the different coatings investigated, the performance of the coatings depends on whether the sheet material is zinc coated or not. However, the CrC/C coating investigated show a good performance with respect to the galling tendency in contact with all of the investigated high strength steel grades.

    List of papers
    1. Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing
    Open this publication in new window or tab >>Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing
    2009 (English)In: Tool09: Tool steels, june 2nd-4th 2009 in aachen, germany, 2009Conference paper, Published paper (Other academic)
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in sheet metal forming, including the development of new dry lubricants, new forming tool steel grades and improved surface engineering treatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potential performance of these concepts in the forming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steel has been evaluated using pin-on disc testing. In the tests, two different lubricants, a dry lubricant and a pre-lube oil, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade, and two different PVD coatings, (Ti,Al)n and CrC/C, were evaluated. Post-test examination of the tribosurfaces using FEG-SEM, EDX and 3D surface profilometry was performed in order to evaluate the mechanisms controlling the material transfer and wear. In summary, the results show that the laboratory testing combined with post-test microscopy and surface analysis give valuable information in order to rank the galling resistance of lubricants, tool steels and PVD-coatings.

    Keywords
    sheet metal forming, high strength steels, galling, dry lubricant, tool steels, PVD-coatings
    National Category
    Metallurgy and Metallic Materials
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-159384 (URN)
    Conference
    Tool09
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2012-07-18
    2. Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing
    Open this publication in new window or tab >>Evaluation of galling resistance for some selected combinations of tool steels / stainless steel sheet materials/ lubricants using pin-on-disc testing
    2010 (English)In: NordTrib 2010: 14th Nordic Symposium on Tribology, Storforsen, Sweden / [ed] Elisabet Kassfeldt, 2010Conference paper, Published paper (Refereed)
    Abstract [en]

    Stainless steels are well known to be prone to cold welding and material transfer in sliding contacts and therefore difficult to cold form unless certain precautions as discussed in this paper are taken. In the present study different combinations of tool steels/stainless steels/lubricants has been evaluated with respect to their galling resistance using pin-on-disc testing. The results show that a high galling resistance is favored by a high stainless steel sheet hardness and a blasted stainless steel sheet surface topography. The effect of type of lubricant was found to be more complex. For example, the chlorinated lubricants failed to prevent metal-to-metal contact on a brushed sheet surface but succeeded on a blasted sheet surface of the same stainless steel material. This is believed to be due to a protective tribofilm which is able to form on the blasted surface, but not on the brushed surface.

    Keywords
    Galling, stainless steels, cold work tool steels, lubricants
    National Category
    Metallurgy and Metallic Materials
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-159385 (URN)
    Conference
    NordTrib 2010
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2016-04-18
    3. Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.
    Open this publication in new window or tab >>Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: Evaluation of galling and wear characteristics against different high strength steels.
    2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 16, p. 4045-4051Article in journal (Refereed) Published
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminatedproblems associated with galling in sheet metal forming operations. Galling is a tribological phenomenonassociated with transfer of material from the steel sheet to the tool surface during forming resulting in seizureof the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number ofconcepts have been developed in order to reduce the tendency of galling in sheet metal forming, including thedevelopment of new dry lubricants, new forming tool steel grades and improved surface engineeringtreatments such as the deposition of low friction CVD- and PVD-coatings. In the present study the potentialperformance of three commercial PVD coatings, including CrN, (Ti,Al)N and a CrC/C DLC-based coating, in theforming of hot and cold rolled high strength steel as well as electro and hot-dip galvanized high strength steelhas been evaluated using pin-on-disc testing under lubricated contact conditions. Post-test examination ofthe tribosurfaces using FEG-SEM and EDS analyses was performed in order to evaluate the mechanismscontrolling the tendency to material transfer and wear. The results show that in contact with the hot and coldrolled steel the material pick-up tendency of the PVD coatings tend to increase in the order CrC/C–CrN–(Ti,Al)N while in contact with the two galvanized steel sheets, the CrC/C and the (Ti,Al)N coating show a significantlylower material pick-up tendency as compared with the CrN coating. Further, the substrate hardness has astrong influence on the wear of the PVD coatings and consequently on the friction characteristics and gallingtendency of the coating/substrate composite. Low substrate hardness, resulting in a low load bearing capacity,increases the tendency to cracking and subsequently chipping of the brittle coating.

    Keywords
    PVD coatings, tool steel, high strength steel sheet, galling, friction, wear.
    National Category
    Metallurgy and Metallic Materials
    Research subject
    Engineering Science with specialization in Tribo Materials
    Identifiers
    urn:nbn:se:uu:diva-159386 (URN)10.1016/j.surfcoat.2011.02.053 (DOI)
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
  • 19.
    Fallqvist, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Olsson, M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Nucleation and growth of CVD α-Al2O3on TixOy templateIn: Surface and Coatings TechnologyArticle in journal (Refereed)
  • 20.
    Fallqvist, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    CVD of bonding and template layers for thenucleation of well adhering α-Al2O32012In: Surface and Coatings TechnologyArticle in journal (Refereed)
  • 21.
    Fallqvist, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of CVD Al2O3 coated tool surface micro topography on the tribological characteristics in metal cutting – Part I2012In: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed)
  • 22.
    Fallqvist, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of CVD Al2O3 coated tool surface micro topography on the tribological characteristics in metal cutting – Part II2012In: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed)
  • 23.
    Filho, Luimar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Schmidt, Susann
    IHI Ionbond AG, Ind Str 211, CH-4600 Olten, Switzerland;Linkoping Univ, Thin Film Phys Div, Dept Phys Chem & Biol IFM, S-58183 Linkoping, Sweden.
    Leifer, Klaus
    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.
    Högberg, Hans
    Linkoping Univ, Thin Film Phys Div, Dept Phys Chem & Biol IFM, S-58183 Linkoping, Sweden.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Towards Functional Silicon Nitride Coatings for Joint Replacements2019In: Coatings, ISSN 2079-6412, Vol. 9, no 2, article id 73Article in journal (Refereed)
    Abstract [en]

    Silicon nitride (SiNx) coatings are currently under investigation as bearing surfaces for joint implants, due to their low wear rate and the good biocompatibility of both coatings and their potential wear debris. The aim of this study was to move further towards functional SiNx coatings by evaluating coatings deposited onto CoCrMo surfaces with a CrN interlayer, using different bias voltages and substrate rotations. Reactive direct current magnetron sputtering was used to coat CoCrMo discs with a CrN interlayer, followed by a SiNx top layer, which was deposited by reactive high-power impulse magnetron sputtering. The interlayer was deposited using negative bias voltages ranging between 100 and 900 V, and 1-fold or 3-fold substrate rotation. Scanning electron microscopy showed a dependence of coating morphology on substrate rotation. The N/Si ratio ranged from 1.10 to 1.25, as evaluated by X-ray photoelectron spectroscopy. Vertical scanning interferometry revealed that the coated, unpolished samples had a low average surface roughness between 16 and 33 nm. Rockwell indentations showed improved coating adhesion when a low bias voltage of 100 V was used to deposit the CrN interlayer. Wear tests performed in a reciprocating manner against Si3N4 balls showed specific wear rates lower than, or similar to that of CoCrMo. The study suggests that low negative bias voltages may contribute to a better performance of SiNx coatings in terms of adhesion. The low wear rates found in the current study support further development of silicon nitride-based coatings towards clinical application.

  • 24.
    Fondell, Mattis
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, Berlin 12489, Germany.
    von Fieandt, Linus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Boman, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Phase control of iron oxides grown in nano-scale cauliflower structures: hematite, maghemite and magnetiteManuscript (preprint) (Other academic)
    Abstract [en]

    We demonstrate that iron oxide in the form of hematite, suitable as absorber in photoelectrochemical cells, can be produced by pulsed chemical vapour deposition. By choosing carbon monoxide or nitrogen as carrier gases in the process the phase and granularity of the grown material can be controlled. The choice of carrier gas a ect the decomposition rate of iron pentacarbonyl used as iron precursor. The iron oxide phase is also dependent on the chosen substrate, here fluorine doped tin oxide and crystalline silicon have been used. Regardless of the substrate nitrogen yields hematite, whereas carbon monoxide gives magnetite on Si and maghemite on fluorine doped tin oxide. A combination of Raman spectroscopy, X-ray di raction, and hard X-ray photoelectron spectroscopy were used for characterization of the crystalline phase and chemical composition in the films. Scanning electron microscopy were used to visualise the deposited films’ nano-structure reminiscent of a cauliflower.

  • 25.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Diamond Microfabrication for Applications in Optics and Chemical Sensing2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Diamond is a material with many exceptional properties. In this thesis methods for fabrication of microstructures as well as several applications of such structures in optics, microfluidics and electrochemistry are presented.

    A method for etching deep and highly precise gratings is described. This method was used to fabricate circularly symmetric half wave plates for use in vector vortex coronagraphs. Such coronagraphs are a very promising approach to the direct imaging of extrasolar planets.

    By varying the lateral etch rate of the aluminum mask during diamond etching in an inductively coupled plasma, the sidewall angle of the etched structures could be controlled. This method was used to make smooth sloped sides on a waveguide for coupling light into it. Antireflective structures that drastically reduced the surface reflection in a wavelength band between 10 and 50 µm were also fabricated.

    An array of boron doped diamond microelectrodes for electrochemical measurements in a microchannel was fabricated and tested, showing very good stability and reusability. Several hundred hours of use did not adversely affect their performance and no damage to them could be detected by atomic force microscopy or scanning electron microscopy.

    Superhydrophobic surfaces in diamond were demonstrated, using both hydrogen and fluorine termination. Hydrogen termination on a flat surface gives contact angles below 90°. To achieve a superhydrophobic surface with this low intrinsic hydrophobicity, structures looking like microscopic nail heads were fabricated. The effect of water pressure on immersed superhydrophobic surfaces was also studied and it was found that the collapse of the superhydrophobic state due to pressure was sometimes reversible as the pressure was lowered.

    Finally, a method was tested for functionalizing diamond surfaces using block copolymers of polyethylene oxide and polypropylene oxide to both passivate the surface and to attach synthetic binder molecules. This method was found to give very high signal to noise ratios when detecting C-reactive protein.

    List of papers
    1. High aspect ratio optical gratings in diamond
    Open this publication in new window or tab >>High aspect ratio optical gratings in diamond
    2013 (English)In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 34, p. 19-24Article in journal (Refereed) Published
    Abstract [en]

    In this paper we describe a process for fabricating high aspect ratio gratings in single- or polycrystalline diamond with the high precision required by micro-optics. Nanoimprint lithography with a soft stamp and several layers of hard masks allowed for rapid and accurate replication of patterns written by e-beam or laser into thick Al masks on diamond substrates as large as 2 cm in diameter. Vertical sidewalls in the mask were crucial for avoiding microvilli formation during diamond plasma etching and were achieved by etching and oxidizing the Al mask in cycles. Circularly symmetric half-wave plates for wavelength bands around 4 and 11 mu m were fabricated with deep circular gratings on one side and antireflective gratings on the other.

    Keywords
    Reactive ion etching, synthetic diamond, plasma etching, grating, optics, interface structure
    National Category
    Manufacturing, Surface and Joining Technology Astronomy, Astrophysics and Cosmology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-192561 (URN)10.1016/j.diamond.2013.01.009 (DOI)000317795400004 ()
    Available from: 2013-01-22 Created: 2013-01-22 Last updated: 2017-12-06Bibliographically approved
    2. Design, manufacturing, and performance analysis of mid-infrared achromatic half-wave plates with diamond subwavelength gratings
    Open this publication in new window or tab >>Design, manufacturing, and performance analysis of mid-infrared achromatic half-wave plates with diamond subwavelength gratings
    Show others...
    2012 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 51, no 24, p. 5897-5902Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we present a solution for creating robust monolithic achromatic half-wave plates (HWPs) for the infrared, based on the form birefringence of subwavelength gratings (SWGs) made out of diamond. We use the rigorous coupled wave analysis to design the gratings. Our analysis shows that diamond, besides its outstanding physical and mechanical properties, is a suitable substrate to manufacture mid-infrared HWPs, thanks to its high refractive index, which allows etching SWGs with lower aspect ratio. Based on our optimized design, we manufactured a diamond HWP for the 11-13.2 mu m region, with an estimated mean retardance similar to 3.143 +/- 0.061 rad ( 180.08 +/- 3.51 degrees). In addition, an antireflective grating was etched on the backside of the wave plate, allowing a total transmittance between 89% and 95% over the band.

    National Category
    Physical Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-182532 (URN)10.1364/AO.51.005897 (DOI)000308076600020 ()
    Available from: 2012-10-12 Created: 2012-10-11 Last updated: 2017-12-07Bibliographically approved
    3. Laboratory demonstration of a mid-infrared AGPM vector vortex coronagraph
    Open this publication in new window or tab >>Laboratory demonstration of a mid-infrared AGPM vector vortex coronagraph
    Show others...
    2013 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 553, p. A98-Article in journal (Refereed) Published
    Abstract [en]

    Context. Coronagraphy is a powerful technique to achieve high contrast imaging, hence to image faint companions around bright targets. Various concepts have been used in the visible and near-infrared regimes, while coronagraphic applications in the mid-infrared nowadays remain largely unexplored. Vector vortex phase masks based on concentric subwavelength gratings show great promise for such applications.

    Aims. We aim at producing and validating the first high-performance broadband focal plane phase mask coronagraphs for applications in the mid-infrared regime, and in particular the L band with a fractional bandwidth of  ~16% (3.5–4.1 μm).

    Methods. Based on rigorous coupled wave analysis, we designed an annular groove phase mask (AGPM) producing a vortex effect in the L band, and etched it onto a series of diamond substrates. The grating parameters were measured by means of scanning electron microscopy. The resulting components were then tested on a mid-infrared coronagraphic test bench.

    Results. A broadband raw null depth of 2 × 10-3 was obtained for our best L-band AGPM after only a few iterations between design and manufacturing. This corresponds to a raw contrast of about 6 × 10-5 (10.5 mag) at 2λ/D. This result is fully in line with our projections based on rigorous coupled wave analysis modelling, using the measured grating parameters. The sensitivity to tilt and focus has also been evaluated.

    Conclusions. After years of technological developments, mid-infrared vector vortex coronagraphs have finally become a reality and live up to our expectations. Based on their measured performance, our L-band AGPMs are now ready to open a new parameter space in exoplanet imaging at major ground-based observatories.

    Keywords
    coronagraph diamond
    National Category
    Astronomy, Astrophysics and Cosmology Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-192563 (URN)10.1051/0004-6361/201321126 (DOI)000319858700098 ()
    Available from: 2013-01-22 Created: 2013-01-22 Last updated: 2017-12-06Bibliographically approved
    4. Inclined surfaces in diamond: broadband antireflective structures and coupling light through waveguides
    Open this publication in new window or tab >>Inclined surfaces in diamond: broadband antireflective structures and coupling light through waveguides
    2013 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 3, p. 2693-2700Article in journal (Refereed) Published
    Abstract [en]

     Control of the sidewall angle of diamond microstructures was achieved by varying the gas mixture, bias power and mask shape during inductively coupled plasma etching. Different etch mechanisms were responsible for the angle of the lower and upper part of the sidewall formed during diamond etching. These angles could to some extent be controlled separately. The developed etch process was used to fabricate wideband antireflective structures with an average transmission of 96.4% for wavelengths between 10 and 50 mu m. Smooth facetted edges for coupling light through waveguides from above were also demonstrated. 

    Keywords
    diamond, etching, waveguide, antireflection
    National Category
    Manufacturing, Surface and Joining Technology Other Physics Topics
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-192566 (URN)10.1364/OE.21.002693 (DOI)000315991400015 ()
    Available from: 2013-01-22 Created: 2013-01-22 Last updated: 2017-12-06
    5. Designed protein binders in combination with nanocrystalline diamond for use in high-sensitivity biosensors
    Open this publication in new window or tab >>Designed protein binders in combination with nanocrystalline diamond for use in high-sensitivity biosensors
    Show others...
    2012 (English)In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 404, no 6-7, p. 1643-1651Article in journal (Refereed) Published
    Abstract [en]

    A platform for diagnostic applications showing signal-to-noise ratios that by far surpass those of traditional bioanalytical test formats has been developed. It combines the properties of modified nanocrystalline diamond (NCD) surfaces and those of polyethylene oxide and polypropylene oxide based block copolymers for surface passivation and binder conjugation with a new class of synthetic binders for proteins. The NCD surfaces were fluorine-, hydrogen-, or oxygen-terminated prior to further biofunctionalization and the surface composition was characterized by X-ray photoelectron spectroscopy. In a proof of principle demonstration targeting the C-reactive protein, an ELISA carried out using an F-terminated diamond surface showed a signal-to-noise ratio of 3,900 which compares well to the signal-to-noise of 89 obtained in an antibody-based ELISA on a polystyrene microtiter plate, a standard test format used in most life science laboratories today. The increase in signal-to-noise ratio is to a large extent the result of extremely efficient passivation of the diamond surface. The results suggest that significant improvements can be obtained in standardized test formats using new materials in combination with new types of chemical coatings and receptor molecules.

    Keywords
    Protein binders, Nanocrystalline diamond, CRP, Biosensor, Surface characterization
    National Category
    Natural Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-184455 (URN)10.1007/s00216-012-6245-7 (DOI)000309348400004 ()
    Available from: 2012-11-09 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
    6. From Hydrophilic to Superhydrophobic: Fabrication of Micrometer-Sized Nail-Head-Shaped Pillars in Diamond
    Open this publication in new window or tab >>From Hydrophilic to Superhydrophobic: Fabrication of Micrometer-Sized Nail-Head-Shaped Pillars in Diamond
    2010 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 2, p. 889-893Article in journal (Refereed) Published
    Abstract [en]

    The hydrophobicity of microtextured diamond surfaces was investigated. Pillarlike structures were fabricated in both nanocrystalline diamond and microcrystalline diamond. By changing the surface termination of the textured diamond surface, we could switch between superhydrophobic surfaces and hydrophilic surfaces. Examined terminations were hydrogen, fluorine, and oxygen. To evaluate the wetting properties, advancing and receding contact angles were measured. By designing pillars with a wide diamond top on a narrower silicon stem, superhydrophobicity was achieved even when the advancing contact angle on the unstructured diamond surface was below 70°. The possibility to manipulate the hydrophobicity and the Fresnel reflection simultaneously at an infrared wavelength is also demonstrated.

    Keywords
    superhydrophobic diamond nanocrystalline polycrystalline cassie wenzel
    National Category
    Condensed Matter Physics Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-135623 (URN)10.1021/la902361c (DOI)000273403400038 ()
    Note

    PMID: 19775135

    Available from: 2010-12-07 Created: 2010-12-07 Last updated: 2017-12-11
    7. Cassie-Wenzel and Wenzel-Cassie transitions on immersed superhydrophobic surfaces under hydrostatic pressure
    Open this publication in new window or tab >>Cassie-Wenzel and Wenzel-Cassie transitions on immersed superhydrophobic surfaces under hydrostatic pressure
    2011 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 7, no 1, p. 104-109Article in journal (Refereed) Published
    Abstract [en]

    For incorporating superhydrophobic surfaces in microfluidic systems, it is important to understand the ability of the superhydrophobic state to withstand hydraulic pressure. In this paper we describe experiments to probe the collapse transition on superhydrophobic surfaces completely covered by water, where the air film formed on the surface is closed. Polyethylene foils nanoimprinted with micrometre sized pillars in different geometries and densities are used as the model superhydrophobic surfaces. The pressure required for the transition from Cassie to Wenzel state is measured for all surfaces and also compared to analytical and numerical models. We find that the closed film of trapped air helps stabilise the Cassie state at low pillar densities and that the effect of a small change in pillar sidewall angle can drastically change the collapse behaviour. Finally, the reverse transition, from Wenzel to Cassie state, is observed on densely pillared surfaces at low water pressure.

    National Category
    Physical Chemistry Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-134448 (URN)10.1039/C0SM00595A (DOI)000285360200015 ()
    Available from: 2010-11-26 Created: 2010-11-26 Last updated: 2018-05-28
    8. Fabrication of boron doped diamond microband electrodes for electrochemical detection in a microfluidic channel
    Open this publication in new window or tab >>Fabrication of boron doped diamond microband electrodes for electrochemical detection in a microfluidic channel
    Show others...
    2011 (English)In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 20, no 8, p. 1121-1124Article in journal (Refereed) Published
    Abstract [en]

    The manufacturing and electrochemical characterisation of an array of 20 boron doped nanocrystalline diamond (BNCD) microband electrodes for use in a poly(dimethylsiloxane) (PDMS) based microfluidic system are described. The electrodes were fabricated by plasma etching of a silicon oxide- and BNCD thin film coated silicon wafer and the resulting surface structured silicon wafer was subsequently bonded to the PDMS so that the BNCD microband electrodes were located within the PDMS microchannel. The electrochemical performance of the BNCD electrodes was studied and the electrodes were found to exhibit significantly better stability than previously employed gold microband arrays.

    Keywords
    Nanocrystalline, Diamond film, Electrodes, Electrochemical applications, Micro electromechanical systems, Sensors
    National Category
    Engineering and Technology Inorganic Chemistry
    Research subject
    Engineering Science with specialization in Microsystems Technology; Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-160514 (URN)10.1016/j.diamond.2011.06.024 (DOI)000295300800004 ()
    Available from: 2011-10-25 Created: 2011-10-25 Last updated: 2017-12-08
  • 26.
    Forsberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    High aspect ratio optical gratings in diamond2013In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 34, p. 19-24Article in journal (Refereed)
    Abstract [en]

    In this paper we describe a process for fabricating high aspect ratio gratings in single- or polycrystalline diamond with the high precision required by micro-optics. Nanoimprint lithography with a soft stamp and several layers of hard masks allowed for rapid and accurate replication of patterns written by e-beam or laser into thick Al masks on diamond substrates as large as 2 cm in diameter. Vertical sidewalls in the mask were crucial for avoiding microvilli formation during diamond plasma etching and were achieved by etching and oxidizing the Al mask in cycles. Circularly symmetric half-wave plates for wavelength bands around 4 and 11 mu m were fabricated with deep circular gratings on one side and antireflective gratings on the other.

  • 27.
    Forsberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Inclined surfaces in diamond: broadband antireflective structures and coupling light through waveguides2013In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 3, p. 2693-2700Article in journal (Refereed)
    Abstract [en]

     Control of the sidewall angle of diamond microstructures was achieved by varying the gas mixture, bias power and mask shape during inductively coupled plasma etching. Different etch mechanisms were responsible for the angle of the lower and upper part of the sidewall formed during diamond etching. These angles could to some extent be controlled separately. The developed etch process was used to fabricate wideband antireflective structures with an average transmission of 96.4% for wavelengths between 10 and 50 mu m. Smooth facetted edges for coupling light through waveguides from above were also demonstrated. 

  • 28.
    Gustavsson, Fredrik
    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.
    Friction behaviour of Fullerene Like WS2 nanoparticles in a Ni-matrix compared to PVD WS2 and MoS2 coatings2010In: ICMCTF, 2010Conference paper (Refereed)
  • 29.
    Hassila, Carl Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Harlin, P.
    Sandvik Mat Technol AB, Sandviken, Sweden.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Rolling contact fatigue crack propagation relative to anisotropies in additive manufactured Inconel 6252019In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 426-427, no Part B, p. 1837-1845Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing is steadily gaining acceptance in certain industry segments as a process for the manufacturing of dense metallic components. The Ni-based superalloys belonging to the Inconel family have for many years been in focus for AM research and AM produced components are now becoming commercially available. However, it is still unclear how the microstructural anisotropy, inherent to most AM materials, affects the material performance in a given application. The anisotropy may e.g. influence the mechanical properties and the performance in certain tribological situations, such as when subjected to rolling contact fatigue. Like most AM methods, the powder bed fusion - laser beam process gives the produced components a relatively rough surface. To perform well in demanding tribological situations, the components are commonly machined to a smooth finish. In this work, Inconel 625 produced using PBF-LB is evaluated in a rolling contact fatigue test. Test cylinders (empty set 10 mm) have been produced using different build directions and scan strategies, resulting in varying microstructures and textures. In the rolling contact fatigue test, a cylindrical sample is mounted between two empty set 140 mm metal rollers, pulled together via a spring. After testing, the contact tracks are studied using SEM and EBSD to reveal cracks. Cracks were analysed with respect to the microstructure and anisotropies. It was found that the anisotropy influences both the nucleation and growth of cracks. The AM produced specimens were also found to be more prone to transgranular cracking than conventional Inconel 625, which predominantly displayed intergranular cracks.

  • 30.
    Heinrichs, Jannica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mikado, H.
    YKK Corp, Machinery & Engn Grp, Tokyo, Japan.
    Kawakami, A.
    YKK Corp, Machinery & Engn Grp, Tokyo, Japan.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kawamura, S.
    YKK Corp, Machinery & Engn Grp, Tokyo, Japan.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wear mechanisms of WC-Co cemented carbide tools and PVD coated tools used for shearing Cu-alloy wire in zipper production2019In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 420, p. 96-107Article in journal (Refereed)
    Abstract [en]

    To form the individual elements, that together form a zipper, a pre-formed Cu-alloy wire is sheared using cemented carbide tools. The wear caused by the relatively soft copper alloy on the much harder tool is generally quite slow. However, millions of elements are to be sheared so eventually the wear becomes unacceptable and the tool needs to be exchanged. To improve product quality, as well as minimize down time and material consumption, the tool life needs to be prolonged. To achieve this the wear process needs to be better understood. Uncoated tools used for an increasing number of shearing events have been studied in detail using high resolution SEM and EDS, to map the propagating wear and get an insight into the wear mechanisms. Transfer of material from the Cu-alloy to the tool occurs and the wear is highly concentrated to specific areas. This wear occurs on a very fine scale, limited to within individual WC grains at each event. Tools coated with PVD CrC and PVD CrN have been studied for comparison with the uncoated cemented carbide. Both coatings successfully protect the cemented carbide tool from wear, however occasional flaking occurs and then the cemented carbide becomes exposed and subsequently worn. The differences in performance and wear mechanisms between the uncoated and coated tools are discussed, with focus on the capability of the coatings to prolong the tool life.

  • 31.
    Holmstrom, Erik
    et al.
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden.
    Lizarraga, Raquel
    Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.
    Linder, David
    Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.
    Salmasi, Armin
    Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.
    Wang, Wei
    Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.
    Kaplan, Bartek
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden.
    Mao, Huahai
    Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden;Thermocalc Software AB, Rasundavagen 18, SE-16967 Solna, Sweden.
    Larsson, Henrik
    Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden;Thermocalc Software AB, Rasundavagen 18, SE-16967 Solna, Sweden.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden; Dept PhyWigner Res Ctr Phys, Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary.
    High entropy alloys: Substituting for cobalt in cutting edge technology2018In: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 12, p. 322-329Article in journal (Refereed)
    Abstract [en]

    Cemented carbide, also known as hard metal, is one of the most outstanding composite engineering materials since its commercial introduction in the 1920s. The unique combination of strength, hardness and toughness makes cemented carbides highly versatile materials for the most demanding engineering applications. In their simplest form, these materials are composites of tungsten carbide (WC) grains that are cemented with a ductile metallic binder phase, typically cobalt. However, despite the superiority of Co as binder material, there is a long-standing need to find alternative binders due to serious health concerns that have haunted the industry for nearly 80 years. In the present study, we develop a new cemented carbide with a high entropy alloy binder phase (CoCrFeNi) from raw materials to a fully functional, coated and gradient-sintered cutting tool insert. The new hard metal with reduced Co content is designed by using first principles theory and the CALPHAD method. The cutting tool was made by pressing the new hard metal in a standard geometry, sintered to have a thin binder phase enriched surface zone, free from cubic carbides and coated with protective layers of Ti(C,N) and Al2O3. The resulting cutting insert was tested in a real machining operation and compared to a state-of-the-art reference that had Co as binder phase. The cutting tool made of the newly developed cemented carbide has an exceptionally high resistance against plastic deformation at all tested cutting speeds in the machining test, outperforming the reference insert, which shows a linear increase in edge depression when the cutting speed is increased. This result opens up the possibility to utilize the unique properties of high entropy alloys for industrial applications, in particular, as binder phase in new cemented carbides.

  • 32.
    Hubicka, Zdenek
    et al.
    Institute of Physics, ASCR v.v.i., Prague, Czech Republic.
    Cada, Martin
    Institute of Physics, ASCR v.v.i., Prague, Czech Republic.
    Kmet, Stepan
    Institute of Physics, ASCR v.v.i., Prague, Czech Republic.
    Olejnicek, Jiri
    Institute of Physics, ASCR v.v.i., Prague, Czech Republic.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Adamek, Jiri
    Institute of Physics, ASCR v.v.i., Prague, Czech Republic.
    Reactive sputtering of Fe2O3 thin films by high power pulsed plasma systems2012Conference paper (Refereed)
    Abstract [en]

    Semiconductor oxide thin films of Fe2O3 were deposited by reactive sputtering in a high power pulse magnetron and in a pulsed hollow cathode plasma jet sputtering system.  Properties of deposited Fe2O3 were investigated for photocatalytic water splitting applications. Fe2O3 provide a potential to capture a relatively significant portion of the available solar light due to lower band-gap energies. The first system used in this study was the high power pulsed magnetron sputtering system (HIPIMS) employing metallic target of pure iron with outer diameter 50 mm and working in a gas mixture of Ar and O2.  Influence of different magnitudes of the applied pulsed power and pulsing frequency on the formation of crystalline structure, physical properties and photocatalytical properties was investigated.  The maximum pulsed current density used in our reactive HIPIMS magnetron system was ≈ 5 A/cm2. Oxide Fe2O3 thin films were deposited also by a low pressure DC pulsed hollow cathode system. The metallic hollow cathode with internal diameter 5 mm and length 30 mm was sputtered in argon plasma flow and reactive gas oxygen was supplied directly to the reactor. The hollow cathode discharge was supplied from the DC pulsed power supplier working in high power pulsed mode. The maximum attained pulsed current density in our hollow cathode discharge  was approximately  ≈ 3 A/cm2.  The main advantage of this system was the high deposition rate which was nearly independent on the amount of used oxygen in the plasma. A plasma diagnostics was carried out in all the investigated systems. The most important was measurement with various forms of quartz crystal microbalance QCM with several types systems of grids. These systems were used to determine ionization fraction of sputtered and reactively sputtered particle fluxes to the substrate under different deposition conditions of these oxide thin films. The higher ionization fraction of sputtered particles was found for higher current densities in the pulse. In the HIPIMS magnetron, the maximum of ionization fraction of reactively sputtered particles was found around ≈ 60-70% for 5% duty cycle of pulsing frequency. The maximum ionization fraction of sputtered particles in the reactive pulsed hollow cathode system was usually lower than in the investigated reactive HIPIMS magnetron system.

  • 33.
    Johansson, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala Univ, Angstrom Lab, Dept Chem, Inorgan Res Programme, Box 538, SE-75121 Uppsala, Sweden.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetron sputter deposition2018In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 349, p. 529-539Article in journal (Refereed)
    Abstract [en]

    Multicomponent nitride coatings of the Hf-Nb-Ti-V-Zr system with different Hf content (0-18 at.%) were deposited using reactive dc magnetron sputtering. Coatings with lower Hf content (0-7 at.%) were found to consist of a single solid solution phase with NaCl-type structure (space group Fm-3m). Coatings with higher Hf content (10-18 at.%) showed a two-phase material consisting of cubic Fm-3m and tetragonal I4/m:run solid solution phase. The lattice distortion, estimated by calculating the delta-parameter under the assumption of a single solid solution phase, varied between 3.8 and 4.0% and slightly decreased with increasing Hf content. SEM and TEM cross section images showed a columnar microstructure with columns that were frayed on the surface or throughout the whole column. The column size decreased as Hf content increased. The hardness increased from 8 to 19 GPa with increased Hf content, which most probably is related to the change in microstructure rather than change in lattice distortion. The electrical resistivity for all samples ranged between 231 and 286 mu Omega cm.

  • 34.
    Kaplan, B.
    et al.
    Sandvik Coromant R&D, S-12680 Stockholm, Sweden.
    Odelros, S.
    Sandvik Coromant R&D, S-12680 Stockholm, Sweden.
    Kritikos, M.
    Sandvik Coromant R&D, S-12680 Stockholm, Sweden.
    Bejjani, R.
    Sandvik Coromant R&D, S-12680 Stockholm, Sweden.
    Norgren, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Sandvik Coromant R&D, S-12680 Stockholm, Sweden.
    Study of tool wear and chemical interaction during machining of Ti6Al4V2018In: INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, ISSN 0263-4368, Vol. 72, p. 253-256Article in journal (Refereed)
    Abstract [en]

    The present study concerns an investigation of the wear on three uncoated cemented carbide grades, with differing binder content and grain size, during longitudinal turning of Ti6Al4V as a function of cutting speed. The creater wear at end of tool life is studied in detail using electron microscopy and X-ray diffraction. It is observed that decreasing binder content results in slower wear progression and longer tool life. The microstructure of the adhered layer is also dependent on the binder content, where a lower amount of binder results in an increase of dark precipitates in the adhered layer. X-ray diffraction confirms the presence of bcc-W as a chemical wear product at the interface. Diffraction peaks corresponding to cubic (Ti,V)C are also occasionally observed.

  • 35.
    Karlsson, Dennis
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindwall, Greta
    Royal Inst Technol KTH, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Lundback, Andreas
    Lulea Univ Technol, SE-97187 Lulea, Sweden.
    Amnebrink, Mikael
    Sandvik AB, Sandvik Addit Mfg, Box 510, SE-10130 Stockholm, Sweden.
    Bostrom, Magnus
    Sandvik AB, Sandvik Addit Mfg, Box 510, SE-10130 Stockholm, Sweden.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Schuisky, Mikael
    Sandvik AB, Sandvik Addit Mfg, Box 510, SE-10130 Stockholm, Sweden.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Binder jetting of the AlCoCrFeNi alloy2019In: ADDITIVE MANUFACTURING, ISSN 2214-8604, Vol. 27, p. 72-79Article in journal (Refereed)
    Abstract [en]

    High density components of an AlCoCrFeNi alloy, often described as a high-entropy alloy, were manufactured by binder jetting followed by sintering. Thermodynamic calculations using the CALPHAD approach show that the high-entropy alloy is only stable as a single phase in a narrow temperature range below the melting point. At all other temperatures, the alloy will form a mixture of phases, including a sigma phase, which can strongly influence the mechanical properties. The phase stabilities in built AlCoCrFeNi components were investigated by comparing the as-sintered samples with the post-sintering annealed samples at temperatures between 900 degrees C and 1300 degrees C. The as-sintered material shows a dominant B2/bcc structure with additional fcc phase in the grain boundaries and sigma phase precipitating in the grain interior. Annealing experiments between 1000 degrees C and 1100 degrees C inhibit the sigma phase and only a B2/bcc phase with a fcc phase is observed. Increasing the temperature further suppresses the fcc phase in favor for the B2/bcc phases. The mechanical properties are, as expected, dependent on the annealing temperature, with the higher annealing temperature giving an increase in yield strength from 1203 MPa to 1461 MPa and fracture strength from 1996 MPa to 2272 MPa. This can be explained by a hierarchical microstructure with nano-sized precipitates at higher annealing temperatures. The results enlighten the importance of microstructure control, which can be utilized in order to tune the mechanical properties of these alloys. Furthermore, an excellent oxidation resistance was observed with oxide layers with a thickness of less than 5 mu m after 20 h annealing at 1200 degrees C, which would be of great importance for industrial applications.

  • 36.
    Karlsson, Dennis
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Marshal, Amalraj
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Johansson, Filip
    Sandvik Machining Solut AB, Sandvik Addit Mfg, Mossvagen 10, SE-81181 Sandviken, Sweden.
    Schuisky, Mikael
    Sandvik Machining Solut AB, Sandvik Addit Mfg, Mossvagen 10, SE-81181 Sandviken, Sweden.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Schneider, Jochen M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Elemental segregation in an AlCoCrFeNi high-entropy alloy: A comparison between selective laser melting and induction melting2019In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 784, p. 195-203Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing of a high-entropy alloy, AlCoCrFeNi, was studied with selective laser melting from gas atomized powder. A wide process parameter window in the SLM process was investigated but it was impossible to produce crack-free samples, attributed to stresses that originate during the building processes. The microstructure and elemental segregation in the SLM samples were compared with induction-melted AlCoCrFeNi. The induction-melted sample crystallizes in randomly oriented large grains (several hundred microns). Dendritic and inter-dendritic areas with slightly different chemical composition can be observed. Within these areas a spinodal decomposition occurs with a separation into FeCr- and NiAl-rich domains. Further spinodal decomposition within the FeCr-rich regions into Cr- and Fe-rich domains was observed by atom probe tomography.

    In contrast, the SLM-samples crystallizes in much smaller grains (less than 20 μm) with a dendrite-like substructure. These dendrite-like features exhibit distinct chemical fluctuations on the nm-scale. During annealing more pronounced chemical fluctuations and the formation of Cr-rich and Cr-poor regions can be observed. The difference in microstructure and spinodal decomposition between the induction-melted and SLM samples is attributed to the significantly higher cooling rate for SLM. This study shows that, by using different synthesis pathways, it is possible to modify the microstructure and segregation of element within alloys. This can be used to tune the materials properties, if the cracking behavior is handled e.g. by change of alloy composition to minimize phase transformations or use of a heating stage.

  • 37.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Modelling of reactive magnetron sputtering: Towards comprehensive model2012Conference paper (Refereed)
    Abstract [en]

    Modelling of reactive sputtering is a very useful tool to reduce the need for trial-and-error based process optimization as well as to support process development. It also provides a test platform for our understanding of the process. Although the classical "Berg's model" describes the basic behaviour of reactive sputtering remarkably well, there is still a number of open questions regarding the underlying physical processes.

    In this contribution, we first summarize the latest development in the modelling, such as extensions of the basic model taking into account the ion current distribution, various mechanisms of the reactive gas incorporation or process dynamics. Then we briefly describe some of the intriguing experimental results from reactive High Power Impulse Magnetron Sputtering (HiPIMS).

    In order to develop a comprehensive model applicable to reactive HiPIMS, more accurate description of the individual effects taking place in sputtering is essential. A first step in the development of such a model is outlined with focus on the surface processes.

  • 38.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Reactive magnetron sputtering: from fundamentals to high deposition rate processes2013In: Proceedings of the Twelfth th International Symposium on Sputtering & Plasma Processes ISSP 2013 / [ed] Yasuhito Gotoh, 2013, p. 5-9Conference paper (Refereed)
    Abstract [en]

    Reactive magnetron sputtering is widely used for synthesis of various compound thin films. The technique is very versatile and scalable. Especially in industry, high productivity is essential and there is a need for processes with high deposition rates. Achieving high deposition rate and true compound stoichiometry of the deposited film is, however, challenging in reactive sputtering. As a consequence of complex interaction between the reactive gas and the sputtered metal, the relation between deposition rate or composition of the coating and flow of reactive gas is very non-linear and usually exhibits hysteresis behaviour.

    This contribution deals with modelling based development of reactive sputtering processes. First, the basic model of reactive sputtering is briefly reviewed. A steady state model is derived, discussing the most important assumptions and illustrating the physical processes taking place in reactive sputtering. The model is then used to discuss some strategies for high deposition rate processes, such as using high pumping speed or substoichiometric targets. Another strategy for increased deposition rate employs sputtering yield amplification. Here, the sputtering target is doped by a heavy element in order to reduce the depth of collision cascades thus increasing the sputtering yield of target. This technique is suitable for reactive sputtering of oxides as demonstrated for reactive deposition of Al2O3 with W doping. In this case, the deposition rate may be increased by about 100% as confirmed experimentally.

    Although reactive sputtering is well understood, recent research on reactive High Power Impulse Magnetron Sputtering (HiPIMS) brought some intriguing experimental results. In order to develop a comprehensive model applicable to reactive HiPIMS, more accurate description of the individual effects taking place in sputtering is essential. As a first step towards such a model, discharge current behaviour in reactive HiPIMS is analysed. It is shown that in HiPIMS, the discharge behaviour is strongly influenced by ionized particles sputtered from the target.

  • 39.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Cada, Martin
    ASCR, Institute of Physics.
    Hubicka, Zdenek
    ASCR, Institute of Physics.
    Measurement of Ionized Metal Flux Fraction in HiPIMS by Retarding Field QCM Analyzer2014In: 41st International Conference on Metallurgical Coatings and Thin Films, San Diego, CA, April 28 - May 2, 2014, 2014Conference paper (Refereed)
    Abstract [en]

    In this contribution, we describe measurements of the ionized metal flux fraction, the ratio between ionized and neutral metal species, arriving to the substrate in High Power Impulse Magnetron Sputtering (HiPIMS).  The ionized metal flux fraction is determined from the deposition rate of ions and neutrals. In order to determine the respective rates, a combination of a retarding field and by a quartz crystal microbalance (QCM) was used. Two different sensors were tested. A standard QCM equipped with a set of grids and an alternative grid-less sensor which was developed in order to increase the sensitivity. The grid-less sensor uses magnetic field to repel electrons and the bias voltage is applied directly to the QCM top electrode.

    We report results for two materials, Ni and Ti. Ti was characterized both in nonreactive (Ar) and reactive (Ar+O2) atmosphere. Measurements with the QCM analyzer showed an ionized fraction of up to 50% for Ni. Somewhat higher values, exceeding 60%, were measured for Ti. In this case, shorter on times lead to higher ionized fraction at the same deposition rate and average discharge power. In reactive sputtering of Ti, substantially higher ionized fraction was observed in the oxide mode as compared to the metal mode. Already at lower values of the peak power, there was a significant fraction of Ti ions in the oxide mode.

  • 40.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Cada, Martin
    Institute of Physics v.v.i., Academy of Science of the Czech Republic.
    Lundin, Daniel
    Université Paris-Sud.
    Hubicka, Zdenek
    Institute of Physics v.v.i., Academy of Science of the Czech Republic.
    Investigation of ionized metal flux fraction in HiPIMS discharge with Ti and Ni target2013Conference paper (Refereed)
    Abstract [en]

    In deposition of thin film, energetic bombardment during the film growth has a strong impact on the film growth with respect to the film density, adhesion, or internal stresses. Since the energy of impinging ions can be readily controlled by a substrate bias, various means of increasing the ionization degree in sputtering have been investigated. In High Power Impulse Magnetron Sputtering (HiPIMS), high degree of ionization of the sputtered material may be achieved thanks to the high peak powers and thus high plasma densities.

    In this contribution, the ionized metal flux fraction, the ratio between ionized and neutral metal species, arriving to the substrate in HiPIMS was analyzed.  A combination of retarding field analyzer and quartz crystal microbalance (QCM) was used. The QCM sensor can measure the deposition rate from ions and neutrals separately by changing the applied bias voltage allowing for fast determination of the total ionized fraction of material flux to the substrate.

    Two target materials, Ni and Ti were studied, in the case of Ti in both nonreactive (Ar) and reactive (Ar+O2) atmosphere. Measurements with the QCM analyzer showed an ionized fraction of up to 50% for Ni. Somewhat higher values, exceeding 60%, were measured for Ti. In this case, shorter on times lead to higher ionized fraction at the same deposition rate and average discharge power.

    In reactive sputtering of Ti, substantially higher ionized fraction was observed in the oxide mode as compared to the metal mode. Already at lower values of the peak power, there was a significant fraction of Ti ions in the oxide mode. The results are very important for thin film synthesis because show process conditions for ion assisted depositions.

  • 41.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Depla, Diederik
    Ghent University.
    Dynamics of the sputtering target surface evolution in reactive HiPIMS2014In: Invited talk, 14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany, 2014Conference paper (Refereed)
    Abstract [en]

    Reactive High Power Impulse Magnetron Sputtering is a promising deposition technique with many interesting properties. Because of the high plasma densities and dynamic nature of the process, many basic aspects of the ongoing physical processes are still unclear. In this contribution, we study the evolution of the  target surface composition in reactive HiPIMS. Using Ti and Al targets in Ar+O2 and Ar+N2 mixtures, the formation and removal of the corresponding compound at the surface is determined from the time evolution of discharge current waveforms. For comparison, pulsed DC process is also analysed.

    Our results show that the ion dose, required to remove the compound from a poisoned sputtering target, is at least 10 times higher in HiPIMS as compared to pulse DC sputtering. Although the compound removal is comparable for both O and N, target poisoning is much slower in the Ar+N2 atmosphere. The slow cleaning in HiPIMS cannot be explained by sputtering only, as evaluated with simulations using the code TRIDYN. In addition to surface effect, significant fraction of the sputtered reactive gas is “recycled” in the HiPIMS discharge and returns back to the target surface. Because the ultimate goal is to provide a reliable description of the sputtering dynamics, the sputtered flux is analysed by mass spectroscopy.

  • 42.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ericson, Tove
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Scragg, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Reactive magnetron sputtering of precursors for CZTS solar cells2012Conference paper (Refereed)
    Abstract [en]

    At the moment, CIGS (CuInGaSe2) solar cells show the highest efficiency among industrial scale produced thin film solar cells. Given the present strong increase in production, however, the availability and price of indium will become an issue because of its low abundance in Earth's crust. Therefore, there is strong interest in alternative indium free absorber materials. Kesterites CZTS (Cu2ZnSn(SxSe1-x)4) attracted most attention owing to the fact that relatively high efficiencies have already been demonstrated and also due to the similarity to CIGS. In this contribution we report on reactive sputtering for deposition of CZTS precursors. In order to avoid Sn loss at elevated temperatures a two stage process, synthesis of precursor films at relatively low substrate temperature followed by annealing, is used. Depositions are performed by pulsed DC magnetron sputtering from two targets, a CuSn alloy and Zn, in a mixture of Ar and H2S. The film structure is evaluated by X-ray diffraction and Raman spectroscopy while the composition is analysed by RBS, XRF, EDS and EPMA. Internal stress is measured by deflection of thin substrates. Characteristics of the deposition process are discussed with respect to the discharge power, total pressure, substrate temperature and H2S flow on the film structure and composition.

    Sulphur incorporation can be readily controlled by H2S flow with the structure changing from amorphous to columnar with increasing S content. The main issue encountered in the depositions is related to the film composition as the ratio between Cu and Sn does not correspond to the target composition. This effect is discussed in detail with respect to the sputtering and transport through the gas phase. Finally, material properties after annealing are briefly summarized.

  • 43.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Helmersson, Ulf
    Linköping University.
    Lundin, Daniel
    Reactive HiPIMS of Oxides: Hysteresis and Discharge behaviour2014In: Invited talk, 42th International Conference on Metallurgical Coatings and Thin Films, San Diego, CA, April 28 -May 2, 2014, 2014Conference paper (Refereed)
    Abstract [en]

    In High Power Impulse Magnetron Sputtering (HiPIMS), high degree of ionization of the sputtered material is achieved thanks to the high instantaneous peak powers and thus high plasma densities. HiPIMS is therefore beneficial for deposition of dense films, uniform coatings on complex-shaped surfaces as well as interface engineering for improved adhesion. In reactive HiPIMS, compound thin films are deposited from metal targets in an atmosphere of argon and a suitable reactive gas, such as oxygen. As a result of the interaction between sputtered metal and the reactive gas, the relation between the deposition rate and reactive gas flow is nonlinear and typically exhibits hysteresis behaviour.

    This contribution deals with reactive HiPIMS, mainly with the effect of HiPIMS on the hysteresis. First, results from various hysteresis studies are summarized. We show that the frequency dependence indicates an influence of gas rarefaction. The optimum frequency is related with the gas refill time as demonstrated by experiments with targets of different dimensions. Formation of compound at the target surface is also accompanied by a pronounced change in the shape of discharge current waveforms. In HiPIMS, the discharge behaviour is dominated by ionized oxygen sputtered from the target. This is shown from the ion energy distribution functions of different species characterized by energy and time resolved mass spectroscopy.  Finally, we simulate the target surface sputtering by TRIDYN code. The predicted time to completely remove the compound from a target is in reasonable agreement with measurements.

  • 44.
    Kubart, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Moreira, Milena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thin AlN films deposited by reactive HiPIMS and pulsed DC sputtering – a comparative study2014In: 14th International Conference on Plasma Surface Engineering, September 15 - 19, 2014, Garmisch-Partenkirchen, Germany, 2014Conference paper (Refereed)
    Abstract [en]

    High quality wurtzite polycrystalline thin AlN films can be grown at low temperature by reactive magnetron sputtering provided sufficient energy input. Typically, a suitable substrate or a seed layer is used to improve the AlN crystallinity. In this study, thin films grown by pulsed DC (PDCS) and High Power Impulse Magnetron Sputtering (HiPIMS) from an Al target were studied aiming at both higher film quality as well as film deposition in cases where a seed layer is impractical. The deposition process was first characterized with respect to the Ar to N2 gas flow ratio. For selected process conditions, AlN films were prepared with a thickness of about 200 nm.  (100) Si and (110) Mo coated Si substrates were used and no intentional substrate heating was employed. The crystalline texture of the AlN films was determined with various XRD techniques.

    Although the deposition rates with HiPIMS are generally lower than those with PDCS, the transition from metal to compound mode spans over a significantly larger range of N2 gas flow. Therefore, with HiPIMS it is possible to deposit stoichiometric AlN in the transition region at deposition rates comparable with PDCS. Owing to the increased energy input in the HiPIMS process, the film texture is improved which is especially pronounced at low film thicknesses.

  • 45.
    Larsson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gradient formation in cemented carbides with 85Ni:15Fe-binder phase2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

  • 46.
    Liu, Jiangwei
    et al.
    Shandong Univ, Key Lab High Efficiency & Clean Mech Manufacture, Minist Educ, Jinan 250014, Shandong, Peoples R China;Univ Technol Belft Montbeliard, LERMPS, F-90000 Belfort, France.
    Chen, Song
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wang, Yan
    Univ Technol Belft Montbeliard, LERMPS, F-90000 Belfort, France.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Univ Manchester, Sch Elect & Elect Engn, Manchester M13 9PL, Lancs, England.
    Observation and characterisation of the surface hardness enhancement of the laser remelted NiCrBSi coating2018In: International Journal of Surface Science and Engineering, ISSN 1749-785X, E-ISSN 1749-7868, Vol. 12, no 4, p. 336-346Article in journal (Refereed)
    Abstract [en]

    The hardness enhancement on the surface of the laser remelted NiCrBSi coating was observed and characterised by employing X-ray photoelectron microscopy and nanoindentation techniques. The result indicates that, under the line energy density of 80 J/rnm, there is an agglomeration of the borides on the top 20 nm of the remelted coating that significantly enhanced the surface hardness as high as 1.5-fold stronger to 13 GPa than that of the main body of 8.5 GPa. Owing to the high concentration of the borides, the elemental distribution of the remelted surface has been modified significantly. In addition by varying the laser energy, the depth of the surface enhanced regions can be modified.

  • 47.
    Ma, D. L.
    et al.
    Southwest Jiaotong University.
    Wu, B. H.
    Southwest Jiaotong University.
    Deng, Q. Y.
    Southwest Jiaotong University.
    Silins, Kaspars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Chen, C. Z.
    Southwest Jiaotong University.
    Yang, W. M.
    China Academy of Engineering Physics.
    Leng, Y.X.
    Southwest Jiaotong University.
    Huang, N.
    Southwest Jiaotong University.
    Optimal target-sputtering mode for Aluminum Nitride thin film deposition by high power pulse magnetron sputtering (HPPMS)Manuscript (preprint) (Other academic)
  • 48.
    Malmquist, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Prototype manufacturing of microwave components using plastic 3D printing2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The ability to easily customize and produce specialized MW-components for research and industry is a real challenge and the need is identified, as standardized parts have limited use and can limit design freedom. This study aims at exploring if there are simple ways to manufacture rectangular X-band waveguides with operating frequency of 8-12GHz with novel polymer additive manufacturing and chemical metal deposition that can match Computer Numerical Control (CNC) manufactured rectangular metal waveguides in performance. X-band was chosen mostly because of it having a good size to start printing trials and x-band components being in heavy use where a lightweight would be beneficial. Also, to evaluate the manufacturing results by measuring and comparing s-parameters and weight between measuring standard and manufactured waveguides. Furthermore, to use the preexisting models for approximating the attenuation due to surface roughness. Different designs were tested with different polymers and electrodeposition techniques and approaches. Two of the benchmarked techniques gave better results; first, using a modular design with a combination of different polymers and an industrial copper plating technique; second, a single polymer one-piece design using an acrylic carbon paint and a small scale in-house electroless copper deposition. The performance of conventionally manufactured rectangular metal waveguides was not matched but the two investigated techniques show on results that the techniques could possibly be modified in the future to match the performance of conventionally manufactured waveguides.

  • 49.
    Nilsson, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Olsson, M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Microstructure and mechanical properties of materials for the finishing stands of the hot strip mill for steel rollingIn: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed)
  • 50.
    Nilsson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribology in Metal Working2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the tribological performance of tool surfaces in two steel working operations, namely wire drawing and hot rolling. In all forming operations dimensions and surface finish of the products are of utmost importance. Forming basically includes three parts – forming conditions excluded – that may be changed; work material, tool and (possibly) lubricant. In the interface between work material and tool, the conditions are very aggressive with – generally or locally – high temperatures and pressures. The surfaces will be worn in various ways and this will change the conditions in the process. Consequently, the surface finish as well as the dimensions of the formed product may change and in the end, the product will not fulfil the requirements of the customer. Therefore, research and development in regard to wear, and consequently tribology, of the forming tools is of great interest.

    The investigations of wire drawing dies focus on coating adhesion/cohesion, surface characteristics and material transfer onto the coated steel both in laboratory scale as well as in the wire drawing process. Results show that it in wire drawing is possible to enhance the tribological performance of drawing dies by using a lubricant together with a steel substrate coated by a polished, dual-layer coating containing both hard and friction-lowering layers.

    The investigations of hot rolling work rolls focus on microstructure and hardness as well as cracking- and surface characteristics in both laboratory scale and in the hot strip mill. Results show that an ideal hot work roll material should be made up of a matrix with high hardness and a large amount of complex, hard carbides evenly distributed in the microstructure. The surface failure mechanisms of work rolls are very complex involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation.

    This knowledge may be used to develop new tools with higher wear resistance giving better performance, lower costs and lower environmental impact.

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