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  • 1. Berger, Robert
    et al.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Hörnström, Sven Erik
    A comparative study of the corrosion protective properties of chromium and chromium free passivation methods2007Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 202, nr 2, s. 391-397Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Commercially available passivation methods for white-rust protection of hot-dip galvanized steel have been investigated. The passivations were either based on trivalent chromium or chromium free. A chromate based conversion coating was used for reference. The treated panels were tested with regard to white rust protection and paintability. The surface chemistry of the conversion coatings was monitored with scanning Auger electron spectroscopy and X-ray photoelectron spectroscopy. Coating thicknesses were measured using Auger electron sputter depth profiling. The passivations were applied with a thickness recommended by the supplier and thus showed large variation. The thickness of the chromium free passivation (Cr-free) is approximately 75 nm. The coating contains the active ions; H3O+, Ti4+, Mn2+, Zn2+, PO4 3-. The passivation based on trivalent chromium (Cr-III) is approximately 30 nm thick and contains the active ions; H3O+ Cr3+, PO4 3-, F. The chromate based passivation (Cr- VI) is approximately 5 nm thick and contains the active ions Cr6+/Cr3+, F-. The Cr-free and the Cr-III passivations showed similar white rust protection in the corrosion tests. The corrosion resistance was good although it did not fully reach the level of the Cr-VI passivation. The results from the tests of the painted panels showed that the powder paint worked well on all three passivations. The solvent born paint worked best on the passivation based on trivalent chromium. The water born paint showed poor resistance to blistering in the Cleveland humidity test for all three passivations. In this test the passivation with hexavalent chromium showed slightly better results than the chromate free passivations.

  • 2.
    Berger, Robert
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Hörnström, Sven Erik
    Properties of Chromate Free Passivations for Hot-Dip Galvanized Steel2006Inngår i: CORROSION/2006, San Diego, California, USA, 2006Konferansepaper (Annet vitenskapelig)
  • 3.
    Berger, Robert
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Stavlid, N.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    The influence of alkali-degreasing on the chemical composition of hot-dip galvanized steel surfaces2006Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 38, nr 7, s. 1130-1138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of dipping temperature and time on the surface chemistry of hot-dipped galvanized steel sheets during the alkaline degreasing process is investigated. The surface chemistry was monitored with scanning Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The results show high Al concentrations on the untreated surfaces, which are significantly reduced during alkaline degreasing. The same conclusions could be drawn for the carbon compounds that accumulate on the surface during storage. The measurements reveal a gradual reduction in surface Al as the alkali solution temperature and/or degreasing time are increased. When degreasing was conducted at 70 °C for 30 s the surface was practically free from Al, which was present only in small islands. Furthermore, the experiments showed that the thickness of the oxide film covering the surfaces before and after alkaline degreasing is approximately 20 Å. The main constituents of the film varied from ZnAl hydroxide/oxide to Zn hydroxide/oxide, before and after degreasing, respectively. 

  • 4.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Beläggningar till högtemperaturbränsleceller2011Inngår i: Stålforskningsdagarna 2011 / [ed] Joakim Storck, Borlänge: Högskolan Dalarna , 2011, s. 89-99Konferansepaper (Annet vitenskapelig)
    Abstract [sv]

    Det finns en tro om att framtida högtemperaturbränslecellssystem kommer att ha en arbetstemperatur i intervallet 700-850°C. Vid dessa temperaturer kan man utnyttja metalliska material som bipolära plattor i en bränslecellsstack. Det har utvecklats speciella legeringar i just detta syfte men för ytterligare öka på prestandan måste dessa legeringar beläggas med lämpliga föreningar. Syftet med denna artikel är att visa att man kan förbättra olika egenskaperna av ett ferritiskt rostfritt stål genom att belägga det med lämpliga metalliska skikt.

  • 5.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Surface Characterisation Using ToF-SIMS, AES and XPS of Silane Films and Organic Coatings Deposited on Metal Substrates2003Doktoravhandling, monografi (Annet vitenskapelig)
  • 6.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Berger, Robert
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Sundell, Per-Erik
    Johansson, Mats
    Bonding of vegetable oils to mercapto silane treated metal surfaces: surface engineering on the nano scale2006Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 2, s. 838-841Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper the bonding of thin vegetable oil films on mercapto silane treated aluminium surfaces has been studied. The silane molecules are attached to the surface by metal–oxygen–silicon bonds. The coupling between the unsaturated bonds of the vegetable oil and the thiol functionalised surface was obtained through a photoinduced thiol-ene reaction. The surfaces were characterised by X-ray photoelectron spectroscopy (XPS). Vegetable oil contains both saturated and unsaturated carbon chains. For the reactions investigated in this study it is the unsaturated carbon chains that can react by a thiol-ene reaction and the results indicate that it is possible to attach a vegetable oil to a metal surface pre-treated with a thiol functionalised silane.

  • 7.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Carlsson, Per
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Characterisation of Thin Films of a Non-Organofunctional Silane on Al-43.4Zn-1.6Si Alloy Coated Steel by ToF-SIMS1999Inngår i: SIMS XII, Brussels, Belgium, 1999Konferansepaper (Fagfellevurdert)
  • 8.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Carlsson, Per
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Tribological Characterisation of an Organic Coating by the use of ToF-SIMS2003Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 203-204, s. 596-599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ToF-SIMS has been used to analyse tribological induced chemical changes of organic coatings deposited on steel strip hot-dip coated with a 55.0% Al–43.4% Zn–1.6% Si alloy (Aluzink). The organic coating was a styrene–acrylic co-polymer containing different forming additives. The forming properties of the organic coatings were evaluated with modified scratch testing. The friction curves show that organic coated hot-dip coated steel displays significantly better tribological properties, i.e. lower coefficient of friction and lower wear, as compared to hot-dip coated steel. Furthermore, the organic coatings showing the highest material transfer tendency also show the highest wear. ToF-SIMS spectra show that a transfer film consisting of species from the organic coating is formed on the ball counter surface. Finally, a combination of SEM and ToF-SIMS analysis shows that mechanical failure of the coating dominates, i.e. no tribochemical changes of the coatings could be detected in the wear track.

  • 9.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Engkvist, Josefin
    Chalmers University of Technology, Göteborg, Sweden.
    Malmberg, Per
    Chalmers University of Technology, Göteborg, Sweden.
    Comparing 69Ga+ and C60+ for ToF-SIMS sputter depth profiling in a Cr2O3 formed during oxidation of a Ce coated FeCr steel substrate2012Konferansepaper (Annet vitenskapelig)
  • 10.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    A corrosion study of hot-dip galvanized steel sheet pre-treated with gamma-mercaptopropyltrimethoxysilane2007Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 201, nr 8, s. 4734-4742Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work an organofunctional silane, gamma-mercaptopropyltrimethoxysilane (gamma-MPS), has been deposited on hot-dip galvanized cold rolled steel from different silane solution concentrations. Painted and unpainted silane treated samples were corrosion tested and painted samples were adhesion tested. The surface chemistry of the unpainted silane treated samples was investigated with AES, ToF-SIMS and EDS and the surface morphology was studied with SEM. The results show that the silane film thickness is dependent on the silane concentration in the silane solution and a higher silane concentration gives a thicker film. Moreover, thicker films tend to give films with a pronounced crack pattern and even detachment of film debris. Corrosion tests of unpainted samples show that gamma-MPS can not work as a passivation treatment but gives a very good adhesion to the paint

  • 11.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Gelius, Ulrik
    XPS and AES Characterisation of hydrolysed ?- Mercaptopropyltrimethoxysilane deposited on Al, Zn and Al-43.4Zn-1.6Si alloy coated steel2004Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, nr 36, s. 624-631Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Characterisation of a Non-Organofunctional Silane Film Deposited on Al, Zn and Al-43.4Zn-1.6Si Alloy Coated Steel, Part II. Interfacial Characterization by ToF-SIMS and AES2001Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 31, nr 3, s. 223-231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to analyse the interface between a non-organofunctional silane and three different metal substrates (aluminium, zinc and an aluminium-zinc alloy). Ion etching using Ga+ ions was used to expose the interfacial region. Ion fragments from the samples were examined carefully where supposed metal-oxygen-silicon ion fragments should appear in the mass spectra. From high mass resolution spectra it was concluded that there exists an AlOSi+ ion fragment at nominal mass m/z = 71 amu on the aluminium and aluminium-zinc alloy substrates and a ZnOSi+ ion fragment at nominal mass m/z = 108 amu on the zinc and aluminium-zinc alloy substrates. These results are further enhanced by the fact that the characteristic ion pattern of ZnOSi+-type ion fragments, composed of different naturally stable zinc and silicon isotopes, in the mass range m/z = 108-112 amu showed the expected relative peak height relations. The presence of these metal-oxygen-silicon ion fragments is a strong indication that chemical interaction between the silane and the metal substrates exists and that the nature of this interaction is due to the formation of a covalent bond between the silane and the metal substrate. Copyright © 2001 John Wiley & Sons, Ltd.

  • 13.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Characterisation of a Non-Organofunctional Silane Film Deposited on Al, Zn and Al-43.4Zn-1.6Si Alloy-Coated Steel, Part I. Surface Characterization by ToF-SIMS2001Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 31, nr 3, s. 212-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The need to develop new environmentally friendly pretreatments in the surface engineering of metal substrates has become more and more important.This is mainly due to the toxic and carcinogenic properties of the chromium-based surface pretreatments frequently used in the industry. During the last decade, simple solution-dip silane-based pretreatments have emerged as promising candidates for the replacement of currently used pretreatments of metals. Recent investigations have shown that the performance of these newly developed pretreatments is strongly dependent on the chemical composition and structure of the silane film and consequently a lot of work, based on advanced surface analytical techniques, is needed in order to characterize these properties. In the present study, time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to characterize the structure of thin films of the non-organofunctional silane 1,2-bis(triethoxysilyl)ethane (BTSE) deposited on three different metal substrates, i.e. Al, Zn and Al-43.4Zn-1.6Si (AlZn) alloy-coated steel. Of special interest was an evaluation of the influence of substrate material on the structure and composition of the silane films. The results show that the BTSE silane forms a thin, evenly distributed film over the substrate surfaces and that the molecular structure of the silane film is independent of the type of metal substrate. Analysis of the molecular ions in the positive mode shows that the surface structure of the BTSE silane is very complex and that the BTSE condensates via one to three SiOSi bridges. Also, the results show that the BTSE silane is not fully hydrolysed using a hydrolysing time of 1 h. Finally, if an alcohol is used as a solvent for the BTSE there is a clear chemical interaction between the alcohol and the silane, resulting in an exchange of alkoxy groups between the alcohol and the silane. Copyright © 2001 John Wiley & Sons, Ltd.

  • 14.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Time-of-Flight SIMS Characterization of Hydrolysed Organofunctional and Non-Organofunctional Silanes Deposited on Al, Zn and Al-43.4Zn-1.6Si Alloy-Coated Steel2003Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 35, nr 11, s. 880-887Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Jani, Simon
    AB Sandvik Materials Technology, Sandviken, Sweden.
    Lundberg, Mats W.
    AB Sandvik Materials Technology, Sandviken, Sweden.
    Initial oxidation of ferritic interconnect steel, effect due to a thin ceria coating2012Inngår i: European Fuel Cell Forum 2012 - Proceedings (memory stick), 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Today there exist many ferritic stainless steel grades with a chemical composition speciallydesigned to be used as interconnects in solid oxide fuel cell applications in a temperatureinterval of 650-850°C. The steels have good high temperature mechanical properties andcorrosion resistance as well as good electron conductivity in the formed chromium oxidescale.One way to substantially decrease the high temperature degradation of the interconnectsteel i.e. improve properties such as increased surface conductivity and decreasedoxidation and chromium evaporation is to coat the interconnect steel with suitablecoatings. Today it is well known that a thin cobalt coating hinders chromium evaporationand a ceria coating lowers the oxidation rate at high temperature. Thus, by coating theinterconnect steel the properties are improved to an extent that it should be possible to usea cheaper standard steel, e.g. AISI 441, as substrate for the coatings.In this study the ferritic stainless steel alloys Sandvik Sanergy HT and AISI 441 is oxidizedin laboratory air at temperatures at 750°C, 800°C and 850°C. The results show that a welladhered oxide scale of a complex layered structure is formed with significant amounts ofMn, Fe, Cr and Ti in the oxide scale. A Ce coating significantly reduces the growth rate ofthe oxide scale. The lower Cr content in the AISI 441 alloy does not affect the initial hightemperature corrosion properties when coated with Ce. Also, the results demonstrate theusefulness of ToF-SIMS depth profiling for characterisation of the initial stages of oxidationof SOFC materials.

  • 16.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Johansson, M
    Samuelsson, J
    Sundell, P.-E
    A Tribological Study of a Novel Pre-Treatment With Linseed Oil Bonded to Mercaptosilane Treated Aluminium2003Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, nr 166, s. 141-152Artikkel i tidsskrift (Fagfellevurdert)
  • 17.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Johansson, M
    Sundell, P.-E
    Carlsson, Per
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Hellsing, Magnus
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    A ToF-SIMS Study of Linseed Oil Bonded to Mercaptosilane Treated Aluminium2003Inngår i: Proceedings of the 14th International Conference on Secondary Ion Mass Spectrometry, SIMS XIV, San Diego, California, USA, 2003Konferansepaper (Fagfellevurdert)
  • 18.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Lundberg, M.
    High temperature oxidation of plastically deformed ferritic interconnect steel2011Inngår i: ECS Transactions, ISSN 1938-5862, E-ISSN 1938-6737, Vol. 35, nr 1, s. 2463-2470Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, thin sheets of a 22% Cr ferritic steel, Sandvik Sanergy HT has been coated with a thin metallic cobalt film. Samples of the coated steel sheet were exposed to two different forming experiments simulating different aspects of sheet metal forming and post high temperature oxidation. The results show that the metallic cobalt film cracks when the steel sheet is subjected to biaxial straining but that the cracks heal at high temperature. Material subjected to modified scratch testing i.e. simulating the contact between sheet metal and forming tool will oxidize in the same manner as non-scratched material. Also, from high temperature corrosion point of view there is no difference between materials formed under lubricated or dry conditions when oxidized. However, from a tribological point of view a lubricated contact situation is preferred.

  • 19.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Schuisky, Mikael
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Scratch testing as a tool to evaluate the adhesion of thermally grown oxides on ferritic interconnect steel2010Inngår i: 2010 Conference Memory Stick 9th European SOFC Forum, Lucerne, 2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The attempt to decrease the temperature in solid oxide fuel cells has made it possible to use metallic materials as interconnect, i.e. the part that separates the anode and the cathode in a fuel cell stack. Besides being impermeable to gases the interconnect give good electron conduction between adjacent cells and to the external circuit. Thus, the unavoidable oxide scale must have good electron conductivity and therefore good adhesion to the metal since spalling of the oxide scale from the metal will give rise to higher resistance in the whole oxide scale metal system. Scratch testing is today a common technique in order to characterize the mechanical properties of thin hard coatings on various types of substrate materials. In this test the normal load applied on the scratching stylus is continuously increased while the stylus is moved relative the surface. The critical load, corresponding to a cohesive and/or adhesive coating failure is registered either by a change in the force, the acoustic emission signal or preferable by combining the information from signals with post-test characterisation of the scratch using scanning electron microscopy. The present study evaluates the possibilities to use scratch testing as a method to measure or at least quantitatively classify the adhesion characteristics of different types of oxide scales thermally grown on ferritic stainless interconnect steel. Both uncoated and interconnect steel pre-coated with thin metallic coatings are studied. The results show that all oxide layers investigated display a sufficient cohesive strength and adhesion to the underlying substrate and that the major scratching induced surface failure mechanisms are plastic deformation and cracking, i.e. no brittle like chipping or spalling could be observed.

  • 20.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Schuisky, Mikael
    Ravash, Hamed
    Froitzheim, Jan
    Svensson, Jan-Erik
    Chromium evaporation from plastically deformed pre-coated Sandvik Sanergy HT 22% Cr ferritic interconnect steel2010Inngår i: 2010 Conference Memory Stick 9th European SOFC Forum, Lucerne, 2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Ferritic stainless steel has attracted a great deal of attention for its use as an interconnector in solid oxide fuel cells (SOFCs). The ferritic Sandvik Sanergy HT chromium steel is specially developed for interconnectors in SOFC with a unique chemical composition, which gives the alloy a good high temperature corrosion resistance as well as good surface conductivity in the formed chromium oxide scale. However, chromium evaporation from metallic interconnectors in SOFC fuel cells tends to poison the cathode of the fuel cell. Furthermore, the evaporation of chromium species from the oxide surface tends to increase the oxidation rate resulting in increased contact resistance. It is nowadays well known that thin coatings of e.g. cobalt can substantially reduce the chromium evaporation from the interconnectors. In this study, a 22% Cr ferritic steel, Sandvik Sanergy HT has been coated with a thin metallic cobalt film. The coated material was plastically deformed and the effect of chromium evaporation was studied as a function of the degree of deformation. Coated samples are also compared to uncoated material. The results show that the metallic cobalt film cracks when the steel sheet is formed but the chromium evaporation is more or less unaffected.

  • 21.
    Bexell, Ulf
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Stanciu, V.
    Warnicke, P.
    Östh, M.
    Svedlindh, P.
    ToF-SIMS depth profiling of (Ga,Mn)As capped with amorphous arsenic: effects of annealing time2006Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, nr 19, s. 7252-7254Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of annealing time on an amorphous As cap layer and the depth distribution of Mn atoms have been investigated. The results show that a 1600 Å thick As cap layer is completely desorbed after 3 h of annealing time. The depth distributions of Mn indicate that interstitial Mn atoms have diffused to the outer surface and being passivated. The thickness of the Mn passivation layer was around 90 Å.

  • 22. Blomberg, Jonas
    et al.
    Persson, Bengt
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Effects of semi-isostatic densification on anatomy and cell-shape recovery on soaking2006Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 60, nr 3, s. 322-331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Images obtained by scanning electron microscopy (SEM) helped to clarify the question as to how anatomy influences the deformation on compression and the spring-back of densified wood on water soaking. Transverse sections of Norway spruce (Picea abies), Scots pine (Pinus sylvestris), black alder (Alnus glutinosa), Swedish aspen (Populus tremula), European birch (Betula pubescens), European beech (Fagus sylvatica) and pedunculate oak (Quercus robur) were studied. Wood is reinforced with rays in the radial direction and with dense latewood in the tangential direction. When strained radially, rays buckle or tilt tangentially. Softwoods were mainly compressed radially, owing to low number of rays and since latewood is much denser than earlywood. The diffuse-porous hardwoods with low density variation between latewood and earlywood were mainly deformed tangentially, except birch, which has high density at the annual ring border and is mainly compressed radially. The ring-porous hardwoods were relatively equally deformed in the radial and tangential directions because of the high number of rays and high latewood density. Moisture-induced spring-back (shape recovery) was proportional to the degree of compression. Rays remained deformed, which also influenced the surrounding wood. Longitudinal wood cells almost resumed their original shape. Wood with low density and a low degree of compression showed the highest structural recovery. Shearing deformation was particularly pronounced and permanent in woods with high strength anisotropy. Thin-walled and sheared cells, such as earlywood in softwood, tended to crack on compression. Cracks usually stopped at the middle lamella and had a lesser influence on strength properties than for lumen-to-lumen cracks.

  • 23.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Hörnström, Sven Erik
    Corrosion Behaviour of Aluzink with Different Passivation Treatments2001Inngår i: GALVATECH 2001, Brussels, Belgium, 2001Konferansepaper (Annet vitenskapelig)
  • 24.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Automatic Scratch Testing - A New Tool for Evaluating the Stability of Tribological Conditions in Sheet Metal Forming2001Inngår i: GALVATECH 2001, Brussels, Belgium, 2001Konferansepaper (Annet vitenskapelig)
  • 25.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Friction and Wear Mechanisms of Thin Organic Permanent Coatings Deposited on Hot-Dip Coated Steel2001Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 247, nr 1, s. 88-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Adhesive wear, generally defined as ‘wear due to localised bonding between contacting solid surfaces leading to material transfer between the two surfaces or loss from either surface’ is a common phenomenon in many sliding contact tribosystems, e.g. sheet metal forming operations. In these operations, galling, i.e. seizure of the sheet surface caused by transfer of sheet material to the tool surface, is frequently a problem since it may results in scratching of the formed sheet surface and eventually cracking and fracture of the product due to high friction forces. In order to reduce the coefficient of friction and the galling tendency in sheet metal forming operations thin organic coatings has been introduced on the market with the intention of improving the performance of hot-dip coated steel sheet. In summary, these coatings have the potential to increase the formability without additional lubrication and serve as temporary corrosion protection during transportation. In the present study, the friction and wear mechanisms of five different thin organic permanent coatings deposited on hot-dip coated (Zn and 55% Al–Zn) steel sheet is evaluated by modified scratch testing. The results obtained show that this test method permits easy and reproducible evaluation of the tribological properties of thin organic coatings. Further, these coatings show a high potential when it comes to improve the formability of hot-dip coated steel. The results obtained are discussed in relation to the identified friction and wear mechanisms.

  • 26.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Tribological Behaviour of Thin Organic Permanent Coatings Deposited on Hot-Dip Coated Steel Sheet - a Laboratory Study2000Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 132, nr 2-3, s. 169-180Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The forming and handling of hot-dip coated steel sheets is frequently associated with problems such as galling, scratching and discoloration. Recently, a new generation of thin organic coatings has been introduced on the market in order to improve the performance of hot-dip coated steel sheets and reduce these kinds of problems. In summary, these coatings have the potential to increase the formability of the steel sheet without additional lubrication, the anti-finger print properties and the corrosion protection of the product. Besides, they should also provide a pre-treatment for painting, i.e. they can be classified as permanent coatings. In the present study, the tribological behaviour of three different thin organic permanent coatings deposited on hot-dip coated (pure zinc and 55% Al–Zn) steel sheets is evaluated by three different laboratory tests; modified scratch testing, pin-on-disc testing and bending under tension testing. The results obtained show that all tests yield consistent and valuable information concerning the friction and wear properties of the materials and can, therefore, be used in order to study the tribology in sheet metal forming and the performance of different types of permanent coatings. Of the permanent coatings investigated, a pure organic coating shows the lowest coefficient of friction (µ close to 0.1) and the highest wear resistance, thus offering excellent anti-galling properties. In contrast, a mixed organic/inorganic coating displays a relatively high coefficient of friction (µ close to 0.3) and a significantly lower wear resistance. Surface analyses of the tested surfaces show that the thickness and coverage of the thin organic coating play an important role in controlling friction and wear. Furthermore, a thin organic coating optimized for improved formability and handling should display: a high adhesion to the underlying substrate material, a low coefficient of friction, a high load carrying capacity and a high intrinsic wear resistance.

  • 27.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Tribological Performance of Thin Organic Permanent Coatings Deposited on 55%Al-Zn Coated Steel – Influence of Coating Composition and Thickness on Friction and Wear2001Inngår i: Wear, ISSN 0043-16.48, Vol. 251, nr 1-12, s. 1075-1084Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dry lubricants are today increasingly being used in various types of sheet metal forming operations. Among these, permanent coatings, based on organic resins are the only lubricants which have the potential to increase the formability without additional lubrication, serve as temporary corrosion protection during transportation and, finally, serve as a pre-treatment before subsequent painting. In the present study, the influence of coating composition and thickness on the friction and wear behaviour of different thin organic permanent coatings deposited on 55%Al–Zn coated steel sheet have been evaluated by various types of laboratory tests. Surface profilometry, scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and time-of-flight secondary ion mass spectrometry (ToF–SIMS) were used in order to characterise and model the tribological behaviour of the coatings. The results obtained show that the tribological properties of thin organic permanent coatings are strongly influenced by the coating thickness. In order to reduce problems associated with high friction and galling, the coating must be deposited with a uniform thickness, i.e. uncoated regions must be avoided. Furthermore, the addition of various types of additives can be used in order to further improve the tribological performance of these types of coatings.

  • 28.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Klang, Hans
    A study of the initial stages of atmospheric corrosion of formed hot dip zinc coated steel1997Inngår i: EUROCORR-97, Trondheim, Norway, 1997Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Hot-dip zinc coated steel sheet is extensively used to improve the corrosion protection of steel constructions. When the sheet is formed cracks in the zinc coating develop in strained areas. The zinc coating gives a galvanic protection of the steel in damaged areas of the coating and at cut edges of the sheet. The degree of protection is, however, dependent on factors such as the geometry and the area of the defects, the coating thickness, the presence of corrosive ions in the electrolyte and the wet time. In this work we have studied the initial atmospheric corrosion of zinc coated steel in defects on bended and scribed material. The samples were exposed to a cyclic indoor corrosion test developed by Volvo (Volvo standard 1027). Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and Auger electron spectroscopy (AES) were used to monitor the initial stages of corrosion and the growth of corrosion products. The corrosion products were identified as predominantly zinc hydroxycarbonate, zinc hydroxychloride and zinc hydroxide. The amount of corrosion products increases with the size of the damaged area, which suggests that the cathodic reduction of oxygen at the steel substrate controls the corrosion rate.

  • 29.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Klang, Hans
    Initial Atmospheric Corrosion Behavior of Formed Hot Dip Zinc Coated Steel - An Energy Dispersive X-ray Spectroscopy Study1997Inngår i: SCANDEM-97, Gothenburg, Sweden, 1997Konferansepaper (Annet vitenskapelig)
  • 30.
    Engkvist, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    High temperature oxidation of FeCrAl-alloys: influence of Al-concentration on oxide layer characteristics2009Inngår i: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 60, nr 11, s. 876-881Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The superior high temperature oxidation resistance of FeCrAl alloys relies on the formation of a dense and continuous protective aluminium oxide layer on the alloy surface when exposed to high temperatures. Consequently, the aluminium content, i.e. the aluminium concentration at the alloy–oxide layer interface, must exceed a critical level in order to form a protective alumina layer. In the present study the oxidation behaviour of six different FeCrAl alloys with Al concentrations in the range of 1.2–5.0wt% have been characterised after oxidation at 900 8C for 72 h with respect to oxide layer surface morphology, thickness and composition using scanning electron microscopy, energy dispersive X-ray spectroscopy and Auger electron spectroscopy.The results show that a minimum of 3.2wt% Al in the FeCrAl alloy is necessary for the formation of a continuous alumina layer. For Al concentrations in the range of 2.0–3.0wt% a three-layered oxide layer is formed, i.e. an oxide layer consisting of an inner alumina-based layer, an intermediate chromia-based layer and an outer iron oxide-based layer. In contrast, the 1.2wt% Al FeCrAl alloy is not able to form a protective oxide layer inhibiting extensive oxidation.

  • 31.
    Engkvist, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    ToF-SIMS Analysis of a FeCrAl Alumina Forming Alloy2004Inngår i: SIMS Europe 2004, Münster, Germany, 2004Konferansepaper (Annet vitenskapelig)
  • 32.
    Engkvist, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    ToF-SIMS Depth Profiling of Alumnia Formed on a FeCrAl High Temperature Alloy2003Inngår i: Proceedings of the 14th International Conference on Secondary Ion Mass Spectrometry, San Diego, California, USA, 2003Konferansepaper (Fagfellevurdert)
  • 33.
    Engkvist, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Grehk, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Early stages of oxidation of uncoated and PVD SiO2 coated FeCrAl foils2009Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 203, nr 19, s. 2845-2850Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high temperature oxidation characteristics of uncoated and SiO2 PVD-coated FeCrAl foils have been investigated when exposed to laboratory air at 1000 °C during 1, 2, 4, 8, 16, 32 and 60 min. The oxidized samples were characterized using SEM, EDS, AES and SIMS. The results show that the presence of a 100 nm thin SiO2 PVD coating significantly reduces the oxidation rate of the FeCrAl foil during early stages of oxidation. The decreased oxidation rate displayed by the SiO2 coated FeCrAl foil is the result of the SiO2 coating acting as an initial diffusion barrier promoting the formation of a predominantly inward growing Al2O3 layer during oxidation. Additionally, by using EDS analysis together with AES and SIMS depth profiling it was shown that the total concentration of Si in the grown oxide scale decreased during oxidation.

  • 34.
    Engkvist, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap. Chalmers University of Technology, Göteborg, Sweden.
    Israelsson, Niklas
    Chalmers University of Technology, Göteborg, Sweden.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    The initial effect of KCl deposit on alumina scales characterized by ToF-SIMS and AES2013Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 45, nr 1, s. 445-448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A FeCrAl alloy was preoxidized to form a protective alumina scale, and the effect of KCl deposits on the alumina scale was investigated while exposed during 1 and 24 h at 600 °C. However, impurity concentrations in the alumina scale change the ion conductivity and hence affect its protective properties. Therefore, Auger electron spectroscopy and time-of-flight secondary ion mass spectrometry were used to characterize the alumina scales and detect traces of K and Cl. The results showed that K and Cl existed as large sharp-edged crystals surrounded by a dendritic network after 1 h. However, after 24 h, those were dissolved, and K together with Cl was detected only in the outer layer of the duplex alumina scale, which was formed during preoxidation.

  • 35. Eriksson, C.
    et al.
    Börner, K.
    Nygren, H.
    Ohlson, K.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Billerdahl, N.
    Johansson, M.
    Studies by imaging ToF-SIMS of bone mineralization on porous titanium implants after 1 week in bone2006Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, nr 19, s. 6757-6760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anodic oxidation was used to grow porous layers on titanium discs. Six different oxidation procedures were used producing six different surfaces. The implants were inserted in rat bone (tibia) for 7 days. After implant retrieval, mineralization (hydroxyapatite formation) on the implant surfaces was investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Bone tissue around the implants was sectioned and stained. The amount of bone in close apposition to the implant was calculated. The porosity showed great variation between the surfaces. Hydroxyapatite was detected on all surfaces. A slight positive correlation between porosity and mineralization was found, although the most porous surface was not the best mineralized one. Bone had formed around all implants after 7 days. The bone-to-metal contact for the porous implants did not differ significantly from the non-porous control. Porosity is known to influence cellular events. The results indicate that porosity could have an initial, positive influence on bone integration of implants, by stimulating the mineralization process. The methods used were found to be suitable tools for investigation of initial healing around implants in bone.

  • 36.
    Grehk, Mikael
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Berger, Robert
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Investigation of the drying process of linseed oil using FTIR and ToF-SIMS2008Inngår i: Proceedings of the 17th International Vacuum Congress/13th International Conference on Surface Science/Internatinal Conference on Nanoscience and Technology, Stockholm, 2008, Vol. 100Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The drying process of linseed oil, oxidized at 80 oC, has been investigated with rheology measurements, Fourier transformation infrared spectroscopy (FTIR), and time of flight secondary ion mass spectrometry (ToF-SIMS). The drying process can be divided into three main steps: initiation, propagation and termination. ToF-SIMS spectra show that the oxidation is initiated at the linolenic (three double bonds) and linoleic fatty acids (two double bonds). ToF-SIMS spectra reveal peaks that can be assigned to ketones, alcohols and hydroperoxides. In this article it is shown that FTIR in combination with ToF-SIMS are well suited tools for investigations of various fatty acid components and reaction products of linseed oil.

  • 37.
    Grehk, Mikael
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Engkvist, Josefin
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Richter, Jan H
    Karlsson, Patrik G
    Sandell, Anders
    Initial stages of metal-organic chemical-vapor deposition of ZrO2 on a FeCrAl alloy2007Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 6, s. 875-879Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The initial stages of metal-organic chemical-vapor deposition of ZrO2 on a model FeCrAl alloy was investigated using synchrotron radiation photoelectron spectroscopy, X-ray absorption spectroscopy, scanning Auger microprobe, and time of flight secondary mass spectrometry. The coatings were grown in ultra-high vacuum at 400 °C and 800 °C using the single source precursor zirconium tetra-tert-butoxide. At 400 °C the coatings mainly consist of tetragonal ZrO2 and at 800 °C amixed ZrO2/Al2O3 layer is formed. The Almetal diffuses from the FeCrAl bulk to themetal/coating interface at 400 °C and to the surface of the coating at 800 °C. The result indicates that the reactionmechanism of the growth process is different at the two investigated temperatures.

  • 38. Gustavsson, Fredrik
    et al.
    Svahn, Fredrik
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Jacobson, Staffan
    Nanoparticle based and sputtered WS2 low-friction coatings: differences and similarities with respect to friction mechanisms and tribofilm formation2013Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 232, s. 616-626Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    MoS2 and WS2 are widely known intrinsic low-friction materials that have been extensively used and thoroughly investigated in literature. They are commonly produced in the form of sputtered coatings and show extremely low friction coefficients in non-humid environments, but rapidly degrade in humid conditions. Close nested fullerene-like nanoparticles of these materials have been proposed to have better oxidation resistance due to their closed form with the absence of dangling bonds. In the present study, an electrochemically deposited coating consisting of fullerene-like nanoparticles of WS2 embedded in a Ni-P matrix is tested under various loads and humidity conditions and compared with a sputtered WS2 coating with respect to their tribological behavior. The formation of a tribofilm on both surfaces is known to be crucial for the low-friction mechanism of WS2 and the different mechanisms behind this formation for the two types of coatings are investigated. It is shown that despite the completely different transformation processes, the resulting tribofilms are very similar. This is analyzed thoroughly using SEM, AES and TEM. The friction coefficient is known to be lower at higher normal loads for these materials and in the present study the mechanical and chemical responses of the tribofilm to higher normal loads during sliding are investigated. It was observed that the basal planes become aligned more parallel to the surface at higher loads, and that the tribofilm is less oxidized. It is suggested that these mechanisms are connected and are crucial keys to the wear life of these materials. (C) 2013 Elsevier B.V. All rights reserved.

  • 39.
    Hall, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Beglund, Tomas
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Influence of microstructure and hard phase content on the mechanisms of deformation and wear of HIP:ed Stellite® 190 composites2015Konferansepaper (Fagfellevurdert)
  • 40.
    Hall, Josefin
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Fletcher, J. S.
    Canovic, S.
    Malmberg, Per
    Comparing depth profiling of oxide scale on SOFC interconnect-materials using ToF-SIMS with 69Ga+, Bi3+/Cs+ and C60+/C602+ as primary and sputter ions2015Inngår i: Materials at High Temperatures, ISSN 0960-3409, Vol. 32, nr 1-2, s. 133-141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxide scale cross-sections of CeO2 coated FeCr based solid oxide fuel cell interconnect materials were examined using secondary ion mass spectrometry (SIMS) depth profiling. A duplex spinel∶chromia scale was formed after 1 h at 850°C. Ti and ceria were observed between these layers. Additionally, minor concentrations of Mn, Si and Nb were observed at the oxide/metal interface. Furthermore, Al and Ti were concentrated primarily in the metal surface close to the oxide/metal interface. Secondary ion mass spectrometry sputter depth profiles using different ion sources; 69Ga+, Bi3+/Cs+ and C60+/C602+ were compared with TEM oxide scale cross-section and field emission gun–Auger electron spectroscopy depth profiling. Secondary ion mass spectrometry depth profiling with 69Ga+, Bi3+/Cs+ showed decreased secondary ion yields in the metallic matrix. This decrease could be avoided using oxygen flooding. The C60cluster ion depth profiles were less sensitive to type of matrix and gave the best correspondence to the TEM cross-section. However, the impact energy has to be high enough to avoid carbon deposition.

  • 41.
    Hall, Josefine
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Berglund, Tomas
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Influence of Microstructure and Hard Phase Content on the Mechanisms of Deformation and Wear of HIP:ed Stellite® 190 Composites2015Inngår i: Proceedings of 2015 European powder metallurgy congress, Euro PM 2015, Reims, France, 4-7 October 2015, 2015Konferansepaper (Fagfellevurdert)
  • 42.
    Harlin, Peter
    et al.
    Sandvik Materials Technology.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Influence of surface topography of arc-deposited TiN and sputter-deposited WC/C coatings on the initial material transfer tendency and friction characteristics under dry sliding contact conditions2009Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 203, nr 13, s. 1748-1755Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of surface topography of PVD coatings on the initial material transfer tendency and friction characteristics in dry sliding contact conditions has been investigated. A modified scratch test was used to evaluate the material transfer tendency between ball bearing steel and two different PVD coatings, TiN and WC/C, under dry sliding contact conditions. Post test characterisation of the contact surfaces was performed using SEM/EDS and AES in order to map the initiation points and mechanisms for material transfer. The results show that the resulting topography of the PVD coated surfaces is strongly dependent on both the substrate material topography and the topography induced by the coating deposition process used. In sliding contact with a softer surface the coating topography results in a significant material pick-up tendency of the PVD coated surfaces. The material pick-up is mainly controlled by the abrasive action of hard coating asperities and as a result a polishing post treatment of the as-deposited PVD coatings significantly reduces the material pick-up tendency. For the WC/C coating, showing intrinsic low friction properties, the post treatment inhibits the material pick-up and results in a low and stable friction coefficient (mu similar to 0.1). For the TiN coating, that lacks intrinsic low friction properties, the post treatment reduces the material pick-up tendency but has no significant influence on the friction characteristics. This is mainly due to the presence of metallic Ti originating from the macroparticles on the TiN coating which results in a reactive surface that promotes a strong adhesion between the mating surfaces.

  • 43.
    Harlin, Peter
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Carlsson, Per
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Influence of surface roughness of PVD coatings on tribological performance in sliding contacts2006Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 201, nr 7, s. 4253-4259Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of surface roughness on the tribological performance, i.e. friction, wear and material pick-up tendency, of two different commercial PVD coatings, TiN and WC/C, in sliding contact with ball bearing steel has been evaluated using two different types of sliding wear laboratory tests. Post-test characterisation using SEM/EDS, AES, ToF-SIMS and XPS was used to evaluate the prevailing friction and wear. The results show that the surface roughness of the coating is of importance in order to control the initial material pick-up tendency and thus the friction characteristics in a sliding contact. Once initiated, the material pick-up tendency will increase, generating a tribofilm at the sliding interface. For steel–TiN sliding couples a FeO-based tribofilm is generated on the two surfaces and FeO/FeO becomes the sliding interface (interfilm sliding) resulting in a high friction coefficient. For steel–WC/C sliding couples the WC/C displays a pronounced running-in behaviour which generates a WO3-based tribofilm on the steel surface while a carbon rich surface layer is formed on the WC/C surface, i.e. WO3/C becomes the sliding interface (interface sliding) resulting in a low friction coefficient.

  • 44. Heinrichs, J.
    et al.
    Gerth, J.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Larsson, M.
    Wiklund, U.
    Influence from surface roughness on steel transfer to PVD tool coatings in continuous and intermittent sliding contacts2012Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 56, s. 9-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A sliding test is used in order to evaluate the influence of tool surface roughness on the material transfer in intermittent and continuous sliding of PVD coated HSS against case hardening steel (20NiCrMo2). Two cutting tool coatings, TiN and AlCrN, and three different surface roughnesses are tested. For polished surfaces the same types of material transfer are obtained irrespective of sliding mode and coating type. If the surfaces are too rough, the tribofilms do not grow thick enough to separate the surfaces and the work material is abrasively worn in both sliding modes. With increased sliding distance, cracking of the TiN coating occurs while the AlCrN coating remains intact. (C) 2012 Elsevier Ltd. All rights reserved.

  • 45.
    Heinrichs, Jannica
    et al.
    Tribomaterials group, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Gerth, Julia
    Tribomaterials group, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Thersleff, Thomas
    Applied Materials Science, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Larsson, Mats
    Primateria AB, Uppsala, Sweden.
    Wiklund, Urban
    Tribomaterials group, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Influence of sliding speed on modes of material transfer as steel slides against PVD tool coatings2013Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 58, s. 55-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An intermittent sliding test was used in order to study the formation and build- up of tribofilms during intermittent sliding of PVD coated HSS against case hardening steel (20NiCrMo2). Two cutting tool coatings were tested, TiN and AlCrN, and the influence of sliding speed was evaluated. With moderate speed,  two tribofilms were formed separately, one consisting of Mn, Si, Al and O on an intermediate layer  of Fe and one consisting of Fe, Mn, Cr and O on an intermediate layer of Cr and Mn. At low sliding speeds an uneven transfer of steel occured while high sliding speeds resulted in thermal softening of the substrate leading to coating failure. AlCrN provided better substrate protection at high speeds than TiN did.

  • 46. Hultquist, G.
    et al.
    Graham, M. J.
    Kodra, O.
    Moisa, S.
    Liu, R.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Smialek, J. L.
    Corrosion of copper in distilled water without O-2 and the detection of produced hydrogen2015Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 95, s. 162-167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports on hydrogen pressures measured during similar to 19,000 h immersion of copper in oxygen-free liquid distilled water. Copper corrosion products have been examined ex-situ by SEM and characterized by XPS and SIMS. XPS strongly indicates a corrosion product containing both oxygen and hydrogen. SIMS shows that oxygen is mainly present in the outer 0.3 mu m surface region and that hydrogen penetrates to depths well below the corrosion product. Thermal desorption spectroscopy shows that the reaction product formed near room-temperature is less stable than that formed in air at 350 degrees C. 

  • 47. Hultquist, Gunnar
    et al.
    Graham, M. J.
    Kodra, O.
    Moisa, R.
    Liu, R.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Smialek, J. L.
    Corrosion of copper in distilled water without molecular oxygen and the detection of produced hydrogen2013Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper reports on hydrogen pressures measured during the longterm immersion (~19 000 hours) of copper in oxygen-free distilled water. Hydrogen gas evolution is from copper corrosion and similar pressures (in the mbar range) are measured for copper contained in either a 316 stainless steel or titanium system. Copper corrosion products have been examined ex-situ by SEM and characterized by Xray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). XPS strongly indicates a corrosion product containing both hydroxide and oxide. SIMS shows that oxygen is mainly present in the outer 0.3 um surface region and that hydrogen penetrates to depths in the substrate well below the corrosion product.

  • 48. Hörnström, Sven Erik
    et al.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    van Ooij, Wim. J.
    Zhang, J.
    Characterisation of Thin Films of Organofunctional and Non-Functional Silanes on 55Al-43.4Zn-1.6Si Alloy Coated Steel1997Inngår i: ECASIA 97, Gothenburg, Sweden, 1997Konferansepaper (Fagfellevurdert)
  • 49. Johansson, M
    et al.
    Samuelsson, J
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Sundell, P.-E
    Fatty Acid Derivatives in Radiation Curable Coatings2004Inngår i: Proceedings of e|5: UV & EB Technology Conference, Charlotte, NC, USA, 2004Konferansepaper (Fagfellevurdert)
  • 50. Johansson, M
    et al.
    Samuelsson, J
    Sundell, P.-E
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Radiation Induced Polymerization of Monomers From Renewable Resources2003Inngår i: Polymer Preprints, ISSN 0551-4657, Vol. 44, nr 1, s. 19-20Artikkel i tidsskrift (Fagfellevurdert)
12 1 - 50 of 73
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