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  • 1. Berglund, T.
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    High velocity compaction of high speed steel powder: possibilities and constraints2007In: Proceedings of the Euro Powder Metallurgy Congress and Exhibition, Euro PM 2007, 2007, Vol. 3, 21-26 p.Conference paper (Refereed)
    Abstract [en]

    It is known that gas atomized powders as well as high alloyed metal powders are difficult to press into green bodies using conventional quasi static pressing techniques. However, the development of the high velocity compaction (HVC) technique has expanded the possibility to compact a larger spectrum of metal powders. Although the HVC technique has many similarities with conventional pressing techniques, the high energy impact makes it an interesting technique not only for the pressing of conventional metal powders to green bodies of high density but also for the pressing of "difficult to press metal powders". Today, high speed steel (HSS) is increasingly being used in different types of components. Consequently, there is an increasing interest in the near net shape manufacturing of HSS components. The aim of the present study is to evaluate the possibility to utilize HVC to press green bodies from different types of HSS powder covering both gas and water atomized HSS powders. The results show that the HSS powders investigated differ with respect to compaction properties, i.e. compressibility and green body quality. While the water atomized powders exhibit very good compaction properties, resulting in green bodies of high density, good surface finish and high strength, the gas atomized powders cannot be pressed in the as-atomized condition using HVC. However, agglomerated as well as milled gas atomized HSS powders show significant improved compaction properties compared to the as-atomized powders, although all showed defects of varying sizes depending on the applied energy during compaction.

  • 2.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Berger, Robert
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Sundell, Per-Erik
    Johansson, Mats
    Bonding of vegetable oils to mercapto silane treated metal surfaces: surface engineering on the nano scale2006In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 2, 838-841 p.Article in journal (Refereed)
    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.

  • 3.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Characterisation of Thin Films of a Non-Organofunctional Silane on Al-43.4Zn-1.6Si Alloy Coated Steel by ToF-SIMS1999In: SIMS XII, Brussels, Belgium, 1999Conference paper (Refereed)
  • 4.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Tribological Characterisation of an Organic Coating by the use of ToF-SIMS2003In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 203-204, 596-599 p.Article in journal (Refereed)
    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.

  • 5.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Gelius, Ulrik
    XPS and AES Characterisation of hydrolysed ?- Mercaptopropyltrimethoxysilane deposited on Al, Zn and Al-43.4Zn-1.6Si alloy coated steel2004In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, no 36, 624-631 p.Article in journal (Refereed)
  • 6.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    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 AES2001In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 31, no 3, 223-231 p.Article in journal (Refereed)
    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.

  • 7.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    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-SIMS2001In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 31, no 3, 212-222 p.Article in journal (Refereed)
    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.

  • 8.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Time-of-Flight SIMS Characterization of Hydrolysed Organofunctional and Non-Organofunctional Silanes Deposited on Al, Zn and Al-43.4Zn-1.6Si Alloy-Coated Steel2003In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 35, no 11, 880-887 p.Article in journal (Refereed)
  • 9.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    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 coating2012In: European Fuel Cell Forum 2012 - Proceedings (memory stick), 2012Conference paper (Other academic)
    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.

  • 10.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Johansson, M
    Samuelsson, J
    Sundell, P.-E
    A Tribological Study of a Novel Pre-Treatment With Linseed Oil Bonded to Mercaptosilane Treated Aluminium2003In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, no 166, 141-152 p.Article in journal (Refereed)
  • 11.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Johansson, M
    Sundell, P.-E
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Hellsing, Magnus
    Dalarna University, School of Technology and Business Studies, Material Science.
    A ToF-SIMS Study of Linseed Oil Bonded to Mercaptosilane Treated Aluminium2003In: Proceedings of the 14th International Conference on Secondary Ion Mass Spectrometry, SIMS XIV, San Diego, California, USA, 2003Conference paper (Refereed)
  • 12.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Lundberg, M.
    High temperature oxidation of plastically deformed ferritic interconnect steel2011In: ECS Transactions, ISSN 1938-5862, E-ISSN 1938-6737, Vol. 35, no 1, 2463-2470 p.Article in journal (Refereed)
    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.

  • 13.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Schuisky, Mikael
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Scratch testing as a tool to evaluate the adhesion of thermally grown oxides on ferritic interconnect steel2010In: 2010 Conference Memory Stick 9th European SOFC Forum, Lucerne, 2010Conference paper (Other academic)
    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.

  • 14. Borgström, Henrik
    et al.
    Harlin, Peter
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Paiar, Tomaso
    Wang, Yu
    Nyborg, Lars
    Possibilities and constraints of implementing starch consolidated high speed steel in prototyping2008In: Materials Science & Engineering: A, ISSN 0921-5093, Vol. 475, no 1-2, 34-38 p.Article in journal (Refereed)
    Abstract [en]

    In the starch consolidation (SC) process, a water-based slurry containing powder, starch, dispersant and thickener is used to fabricate near net-shape green bodies that are de-binded and further consolidated by sintering. In this study, gas atomized M3/2 as well as high and low carbon V-rich M4 type high speed steel powder (<150 mu m) are considered, Both material types undergo high volumetric shrinkage during super-solidus liquid phase sintering enabling them to reach near full density. The analyses and the review cover different process aspects like: recipe optimisation, post-gelatinization drying, de-binding and sintering. A SC recipe consisting of 58 vol.% powder, 3 vol.% starch, 1 vol.% dispersant and a thickener solution resulted in a density of >98% than what is theoretically stated after sintering. It is found that the success of the post-gelatinization drying procedure depends on the smoothness of mould material and controlling powder oxidation. The best combination was freeze drying the slurry in a silicon rubber mould. For V-rich alloys a total or partial control of eutectic carbides in the final microstructure could be realized for vacuum and nitrogen sintering atmospheres, respectively.

  • 15. Canovic, Sead
    et al.
    Engkvist, Josefin
    Lai, Haiping
    Götlind, Helena
    Svensson, Jan-Erik
    Johansson, Lars-Gunnar
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Microstructural investigation of the water vapour effect on the oxidation of the FeCrAl alloy Kanthal AF at 600 and 800 C2008In: 214th Meeting of ECS - The Electrochemical Society, Honolulu, Hawaii, 2008Conference paper (Other academic)
  • 16. Canovic, Sead
    et al.
    Engkvist, Josefin
    Dalarna University, School of Technology and Business Studies, Material Science.
    Liu, Fang
    Götlind, Helena
    Hellström, Kristina
    Svensson, Jan-Erik
    Johansson, Lars-Gunnar
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Halvarsson, Mats
    Microstructural investigation of the initial oxidation of the FeCrAlRE alloy Kanthal AF in dry and wet O2 at 600 and 800°C2010In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 157, no 6, C223-C230 p.Article in journal (Refereed)
    Abstract [en]

    The FeCrAlRE (where RE is reactive element) alloy Kanthal AF was exposed isothermally at 600 and 800°C for 72 h in dry O2 and in O2 with 10 vol % H2O. The mass gains were 3–5 times higher at the higher temperature. The presence of water vapor increased the oxidation rate at 800°C, while no significant effect was observed at 600°C. A thin two-layered oxide formed at 600°C: an outer (Fe,Cr)2O3 corundum-type oxide, containing some Al, and an inner, probably amorphous, Al-rich oxide. At 800°C a two-layered oxide formed in both environments. The inner layer consisted of inward grown a-Al2O3. In dry O2 the originally formed outward grown g-Al2O3 had transformed to a-Al2O3 after 72 h. Water vapor stabilized the outward grown g-Al2O3 and hence no transformation occurred after 72 h in humid environment. RE-rich oxide particles with varying composition (Y, Zr, and Ti) were distributed in the base oxide at both temperatures and in both environments. The RE-rich particles were separated from the alloy substrate by a layer of Al-rich oxide. At 800°C the Y-rich RE particles were surrounded by thick oxide patches in both dry and humid O2.

  • 17.
    Carlsson, Per
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Automatic Scratch Testing - A New Tool for Evaluating the Stability of Tribological Conditions in Sheet Metal Forming2001In: GALVATECH 2001, Brussels, Belgium, 2001Conference paper (Other academic)
  • 18.
    Carlsson, Per
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Friction and Wear Mechanisms of Thin Organic Permanent Coatings Deposited on Hot-Dip Coated Steel2001In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 247, no 1, 88-99 p.Article in journal (Refereed)
    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.

  • 19.
    Carlsson, Per
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Tribological Behaviour of Thin Organic Permanent Coatings Deposited on Hot-Dip Coated Steel Sheet - a Laboratory Study2000In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 132, no 2-3, 169-180 p.Article in journal (Refereed)
    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.

  • 20.
    Carlsson, Per
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Tribological Performance of Thin Organic Permanent Coatings Deposited on 55%Al-Zn Coated Steel – Influence of Coating Composition and Thickness on Friction and Wear2001In: Wear, ISSN 0043-16.48, Vol. 251, no 1-12, 1075-1084 p.Article in journal (Refereed)
    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.

  • 21.
    Carlsson, Per
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Klang, Hans
    A study of the initial stages of atmospheric corrosion of formed hot dip zinc coated steel1997In: EUROCORR-97, Trondheim, Norway, 1997Conference paper (Other academic)
    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.

  • 22.
    Carlsson, Per
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Klang, Hans
    Initial Atmospheric Corrosion Behavior of Formed Hot Dip Zinc Coated Steel - An Energy Dispersive X-ray Spectroscopy Study1997In: SCANDEM-97, Gothenburg, Sweden, 1997Conference paper (Other academic)
  • 23. Carlsson, Per
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    PVD coatings for sheet metal forming: a tribological evaluation2006In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 200, no 14-15, 4654-4663 p.Article in journal (Refereed)
    Abstract [en]

    The use of liquid-based lubricants in sheet metal forming mutually has a negative impact on the environment and on the whole economy, and, consequently, there is an urgent need to find a solution to make the forming processes dry or nearly dry. The deposition of a low-friction PVD coating on the forming tool has during the last years proved to be an interesting choice when it comes to create an “unlubricated” forming process. In the present study, five different PVD coatings (one CrN and four metal-carbide-doped DLC coatings) have been evaluated in sliding contact against hot dip Zn and 55% Al–Zn-coated steel sheet using a ball-on-disc test. From the investigation, it was found that all DLC coatings have potential to prevent material pickup during dry forming of hot dip Zn-coated steel. However, the as-deposited surface morphology, showing surface irregularities such as droplets and dimples, of the coatings will strongly influence the tribological performance, and, consequently, a polishing treatment or a running-in process, resulting in a smooth surface, will significantly reduce the tendency to material pickup. In sliding contact against 55% Al–Zn-coated steel, all PVD coatings display material pickup and high friction values, the only exception being a CrC-doped DLC coating in the as-polished condition. The CrN coating showed poor performance in sliding contact against both steel sheet materials due to a high tendency to material pickup. The study focuses on the tribo-induced changes of the surface condition of the PVD coating and the steel sheet surface during the sliding event. The changes in surface chemistry and topography of the tribo surfaces were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Auger electron spectroscopy (AES) and light interference profilometry.

  • 24.
    Ceron, Ermanno
    et al.
    Technical University of Denmark.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Bay, Niels
    Technical University of Denmark.
    Lubricant film breakdown and material pick-up in sheet forming of advanced high strength steels and stainless steels when using environmental friendly lubricants2014In: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 966-967, 219-227 p.Article in journal (Refereed)
    Abstract [en]

    Increasing focus on environmental issues in industrial production has urged sheet metal stamping companies to look for new tribo-systems in order to substitute hazardous lubricants such as chlorinated paraffin oils. The efficiency of chlorinated paraffin is due to the fact that the lubricant reacts chemically with the tool and workpiece material forming thin films, which adhere strongly to the surfaces and reduce the tendency to metal-metal contact and material pick-up. Production tests of new, environmentally benign tribo-systems are, however, costly and laboratory tests are preferred as a preliminary simulative method to investigate alternative tribo-systems. The present paper presents a case study where an industrial process, consisting of deep drawing with two subsequent re-drawings, was selected and four potential new tribo-systems were tested including different workpiece materials, i.e. AHSSs and stainless steels. The performance of the tribo-systems was analyzed in the laboratory by means of a newly developed simulative test as well as in an industrial production process. The results obtained show a good agreement between the laboratory test and the industrial production process regarding the tribological performance, i.e. tendency to material pick-up and galling, of the evaluated tribo-systems. Moreover the SEM analysis shows that different workpiece materials result in different types of material pick-up.

  • 25.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    High temperature oxidation of FeCrAl-alloys: influence of Al-concentration on oxide layer characteristics2009In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 60, no 11, 876-881 p.Article in journal (Refereed)
    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.

  • 26.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    ToF-SIMS Analysis of a FeCrAl Alumina Forming Alloy2004In: SIMS Europe 2004, Münster, Germany, 2004Conference paper (Other academic)
  • 27.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    ToF-SIMS Depth Profiling of Alumnia Formed on a FeCrAl High Temperature Alloy2003In: Proceedings of the 14th International Conference on Secondary Ion Mass Spectrometry, San Diego, California, USA, 2003Conference paper (Refereed)
  • 28.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Canovic, S.
    Liu, F.
    Gotlind, H.
    Svensson, J. -E
    Johansson, L. -G
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Halvarsson, M.
    Oxidation of FeCrAl foils at 500-900 degrees C in dry O2 and O2 with 40% H2O2009In: Materials at High Temperature, ISSN 0960-3409, Vol. 26, no 2, 199-210 p.Article in journal (Refereed)
    Abstract [en]

    High temperature resistant FeCrAl alloys are frequently used in high temperature applications Such as heating elements and metal based catalytic converter bodies. When exposed to high temperatures an adherent, slowly growing, dense aluminium oxide layer forms on the surface, which protects the underlying alloy from severe degradation. The composition, structure and properties of the formed oxide layer are strongly dependent on the alloy composition, temperature and oxidation environment. In this study, the Sandvik 0C404 FeCrAl alloy, in the form of 50 mu m thick foils, was exposed isothermally in the temperature range 500-900 degrees C for 168 hours in dry O-2 and in O-2 with 40 vol.% H2O. The surface morphology, composition and microstructure of the grown oxide scales were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), grazing incidence X-ray diffraction (GI-XRD), Auger electron spectroscopy (AES), and time of flight secondary ion mass spectrometry (TOF-SIMS). The oxidation process was faster at 900 degrees C than at 500 and 700 degrees C. At 500 degrees C a thin (10-20 nm) mixed oxide of Fe, Cr and Al was formed. Exposure at 700 degrees C resulted ill a similar (40-50 nm) duplex oxide, in both dry O-2 and in O-2 With 40 vol.% H2O. These oxide scales consisted of all inner and an outer relatively pure alumina separated by a Cr-rich band. This type of duplex oxide scale also formed at 900 degrees C with a thin inward growing alpha-Al2O3 at the oxide/metal interface and an outward growing layer outside a Cr-rich band. However, at 900 degrees C the Outward growing layer showed two types of oxide morphologies; a thin smooth base oxide and a much thicker nodular oxide grown on top of substrate ridges. In dry O-2 atmosphere, the main part of this outward growing layer had transformed to alpha-Al2O3. Only in the outer part of the thick oxide nodules, metastable alumina was found. When exposed in the presence of water vapour the main pall of the metastable alumina remained untransformed.

  • 29.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Canovic, Sead
    Hellström, Kristina
    Järdnäs, Anders
    Svensson, Jan-Erik
    Johansson, Lars-Gunnar
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Halvarsson, Mats
    Alumina scale formation on a powder metallurgical FeCrAl alloy (Kanthal APMT) at 900-1100 °C in dry O2 and in O2 + H2O2010In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 73, no 1-2, 233-253 p.Article in journal (Refereed)
    Abstract [en]

    A Rapidly Solidified Powder (RSP) metallurgical FeCrAl alloy, Kanthal APMT, was exposed in dry and humid O2 for 72 h at 900–1,100 °C. The formed oxide scales were characterized using gravimetry in combination with advanced analysis techniques (SEM, EDX, TEM, XRD, AES andSIMS). The oxide scales were at all exposures composed of two-layered α-Al2O3 scales exhibiting a top layer of equiaxed grains and a bottom layer containing elongated grains. A Cr-rich zone, originating in the native oxide present before exposure, separated these two layers. The top α-Al2O3layer is suggested to have formed by transformation of outwardly grown metastable alumina, while the inward-grown bottom α-Al2O3 layer had incorporated small Zr-, Hf- and Ti-rich oxide particles present in the alloy matrix. The scale also contained larger Y-rich oxide particles. Furthermore, in the temperature range studied, the presence of water vapour accelerated alloy oxidation somewhat and affected scale morphology.

  • 30. Engkvist, Josefin
    et al.
    Canovic, Sead
    Järdnäs, Anders
    Svensson, Jan-Erik
    Johansson, Lars-Gunnar
    Halvarsson, Mats
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Microstructural investigation of the effect of watr vapour on the oxidation of a FeCrAl alloy (Sandvik APMT)2008In: 214th Meeting of ECS-The Electrochemical Society, Honolulu, Hawaii, 2008Conference paper (Other academic)
  • 31.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Canovic, Sead
    Liu, Fang
    Götlind, Helena
    Svensson, Jan-Erik
    Johansson, Lars-Gunnar
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Halvarsson, Mats
    Oxidation of FeCrAl foils at 500-900 C in dry O2 and O2 with 40% H2O2009In: 7th Int. Conf. on the Microscopy of Oxidation, Chester, UK, 2009Conference paper (Other academic)
  • 32.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Early stages of oxidation of uncoated and PVD SiO2 coated FeCrAl foils2009In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 203, no 19, 2845-2850 p.Article in journal (Refereed)
    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.

  • 33.
    Eriksson, Jenny
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Evaluation of galling resistance for some selected combinations of tool steels/stainless steel sheet materials/lubricants using pin-on-disc testing2010In: NordTrib 2010, Storforsen, 2010Conference paper (Other academic)
    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.

  • 34.
    Eriksson, Jenny
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Galling and wear characteristics of some commercial PVD coatings as evaluated by tribological testing2009In: International conferens on metallurgical coatings and thin films (ICMCTF), San Diego, 2009Conference paper (Other academic)
  • 35.
    Eriksson, Jenny
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Galling resistance of some selected tool steel/high strength steel sheet materials as evaluated under lubricated sliding conditions using pin-on-disc testing2009In: Wear of Materials, Las Vegas, 2009Conference paper (Other academic)
  • 36.
    Eriksson, Jenny
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Ranking the performance of lubricants, tool steels and PVD coatings for the forming of high strength steel using pin-on-disc testing2009In: Tool 09, Aachen, 2009Conference paper (Other academic)
  • 37.
    Eriksson, Jenny
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Tribological testing of commercial CrN, (Ti,Al)N and CrC/C PVD coatings: evaluation of galling and wear characteristics against different high strength steels2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 16, 4045-4051 p.Article in journal (Refereed)
    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 of 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 three commercial PVD coatings, including CrN, (Ti,Al)N and a CrC/C DLC-based coating, 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 under lubricated contact conditions. Post-test examination of the tribosurfaces using FEG-SEM and EDS analyses was performed in order to evaluate the mechanisms controlling the tendency to material transfer and wear. The results show that in contact with the hot and cold rolled 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 significantly lower material pick-up tendency as compared with the CrN coating. Further, the substrate hardness has a strong influence on the wear of the PVD coatings and consequently on the friction characteristics and galling tendency 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.

  • 38.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    M’Sauobi, R
    Seco Tools.
    Andersson, J
    Seco Tools.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Mechanical and tribological properties of PVD-coated cemented carbide as evaluated by a new multi-pass scratch testing method2012In: Advances in Tribology, ISSN 1687-5915, E-ISSN 1687-5923, no 305209Article in journal (Refereed)
    Abstract [en]

    A new test method based on multipass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by posttest scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N, and (Al0.7Cr0.3)2O3 coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple, and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping, and spalling characteristics of different coating-substrate composites. The test method can be used as a virtually nondestructive test and, for example, be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.

  • 39.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    The influence of surface defects on the mechanical and tribological properties of VN-based arc-evaporated coatings2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 297, no 1-2, 1111-1119 p.Article in journal (Refereed)
    Abstract [en]

    The influence of surface defects, i.e., droplets and craters, on the mechanical and tribological properties of arc-evaporated VxN coatings deposited on cemented carbide has been investigated in a scratching contact using a diamond stylus and a sliding contact using a stainless steel pin. Post-test characterisation using 3D optical surface profilometry and scanning electron microscopy was performed in order to investigate the mechanical and tribological response of the coatings. The results show that scratch induced coating cracking mainly is restricted to larger droplets showing a low interfacial bonding to the adjacent coating matrix. The influence of coating defects on the cohesive strength, i.e., the tendency to chipping of small coating fragments, was found to be relatively small. In contrast, the presence of defects may have a significant impact on the interfacial adhesive strength, increasing the tendency to spalling. In sliding contact, surface defects such as droplets and craters have a strong impact on the tribological behaviour of the coatings causing abrasive wear of the less hard counter material surface and material transfer to the coating, both mechanisms affecting the friction characteristics of sliding contact tribo systems.

  • 40.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    The role of surface defects on the surface fatigue and tribological characteristics of VxN-PVD coatings in sliding contacts2010In: 14th Nordtrib Conference, Storforsen, 2010Conference paper (Other academic)
    Abstract [en]

    The influence of surface defects in arc-evaporated VxN PVD coatings on the adhesion, surface fatigue resistance, friction and wear characteristics has been investigated in a scratching contact using a diamond stylus and a sliding contact using a stainless steel pin. Post-test characterisation using scanning electron microscopy and 3D optical interferometric surface profilometry was performed in order to investigate the mechanical and tribological response of the coatings. The results show that surface defects such as droplets and craters show a strong influence on the tribological behaviour of the coatings causing abrasive wear of the counter surface and material pick-up on the coating surface. In contrast, the influence on the mechanical properties of the coatings, i.e. cracking behaviour, fatigue resistance, etc, was found to be relatively small and cracking seems to be restricted to larger droplets showing a low interfacial bonding to the adjacent coating matrix.

  • 41.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Andersson, Jon
    Msauobi, Rachid
    The influence of surface topography on the formation of build-up layers and wear of CVD-Al2O3 coatings2009In: Wear of Materials, Las Vegas, 2009Conference paper (Other academic)
    Abstract [en]

    During the last years it has become more and more obvious that the surface topography and surface texture strongly influences the performance of CVD and PVD coated cutting tools. As a result the interest for different types of pre- and post-surface treatments of the substrates and the deposited coatings has increased. In the present study the friction and wear characteristics of CVD a-Al2O3 coated cemented carbide exposed to different post-surface treatments, including grinding, wet and dry micro-blasting and polishing, have been investigated using modified scratch testing and pin-on-disc testing using , AISI 304 stainless steel, AISI A2 tool and steel reinforcing iron as counter materials. The influence of the coating surface topography/texture on the resulting friction characteristics, tendency to build up layer formation and prevailing wear mechanisms were identified by optical profilometry, FEG-SEM and EDX analysis. Based on the results obtained, the potential of pin-on-disc testing in the tribological characterisation of CVD coatings for cutting tool applications is discussed.

  • 42.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Ruppi, S
    Abrasive wear of textured-controlled CVD a-Al2O3 coatings2007In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 202, no 4-7, 837-843 p.Article in journal (Refereed)
    Abstract [en]

    In the present study the wear resistance of some CVD alpha-Al2O3 coatings with different growth textures, i.e. <0001>, <10<(1)over bar>2> and <10<(1)over bar>4>, and a kappa-Al2O3 coating have been investigated using a micro-abrasion test with diamond particles as the abrasive medium. The results show that the softer kappa-Al2O3 coating shows a higher wear rate as compared with the textured alpha-Al2O3 coatings. Of the latter coatings, the 101¯4 textured a-Al2O3 coating shows the lowest wear rate while the <0001> and <10<(1)over bar>2> textured alpha-Al2O3 coatings show similar wear rate. Two different dominant wear mechanisms, i.e. micro cutting and micro chipping, were observed and the latter mechanism is believed to control the wear rate of the Al2O3 coatings investigated. The results obtained are discussed in relation to the dominant wear mechanisms of the coatings identified using scanning electron microscopy.

  • 43.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Ruppi, Sakari
    Abrasive wear of multilayer kappa-Al2O3-Ti(C,N) CVD coatings on cemented carbide2007In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 263, no 1-6, 74-80 p.Article in journal (Refereed)
    Abstract [en]

    In the present study the wear resistance of kappa-Al2O3–Ti(C,N) multilayer CVD coatings with different multilayer structures (8, 15, 32 layers of kappa-Al2O3 separated by thin Ti(C,N) layers) have been investigated using a micro-abrasion and a cutting test. The results show that the wear rate of the kappa-Al2O3 multilayer coatings tend to decrease with decreasing layer thickness in the micro-abrasion test and decrease with increasing layer thickness in the cutting tests. The reason for this is mainly due to the difference in wear behaviour depending on temperature. The results obtained are discussed in relation to the dominant wear mechanisms of the coatings which have been identified using scanning electron microscopy and energy dispersive X-ray spectroscopy. The potential of the micro-abrasion test in the characterisation of thin CVD coatings for cutting tool applications is discussed.

  • 44.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Ruppi, S
    Seco Tools.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Ottosson, M
    Uppsala Universitet.
    Grehk, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Sandvik Materials Technology.
    Nucleation and growth of CVD α-Al2O3on TixOy template2012In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 207, 254-261 p.Article in journal (Refereed)
    Abstract [en]

    The microstructure, phase and chemical composition of TixOy templates used to nucleate α-Al2O3 on Ti(C,N) coated cemented carbide have been elucidated using scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry. Further, the adhesive strength of the α-Al2O3–TixOy–Ti(C,N) interfaces was investigated using scratch adhesion testing.

    The present study confirmed that the as-deposited template consisted of a Ti4O7 phase which during subsequent deposition of the Al2O3 layer transformed to a Ti3O5 phase and that the grown Al2O3 layer consisted of 100% α-Al2O3. Furthermore, the results showed that the lowest interfacial strength within the multilayer structure was exhibited by the Ti(C,N)–TixOy interface and that the transformation of Ti4O7 to Ti3O5 in the template resulted in formation of pores in the Ti(C,N)-template interface lowering the interfacial strength even more. The use of surface analysis techniques such as Auger electron spectroscopy and especially Time-of-Flight Secondary Ion Mass Spectrometry enabled trace element analyses using depth profiling to characterise the thin interfacial layers in detail.

  • 45.
    Fallqvist, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Schultheiss, F
    Lunds Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    M’Sauobi, R
    Seco Tools.
    Ståhl, J E
    Lunds Universitet.
    Influence of CVD Al2O3 coated tool surface micro topography on the tribological characteristics in metal cutting: part I2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, 87-98 p.Article in journal (Refereed)
    Abstract [en]

    The influence of surface micro topography of CVD α-Al2O3 coatings, deposited on cemented carbide inserts, on tribological characteristics in sliding contact and in metal cutting has been investigated using quenched and tempered steel as counter/work material. Pin-on-disc and turning tests were carried out and post-test characterization using 3D optical surface profilometry and scanning electron microscopy was performed in order to investigate the tribological response of the coatings. The results show that surface micro topography can have a significant impact on the tribological performance of Al2O3 coatings under initial and cutting contact conditions. For both kinds of tests the tendency for transfer of workpiece material strongly increases with increasing coating micro topography. In the pin-on-disc tests, a smooth coating surface significantly reduces the friction coefficient. In the turning tests the contact conditions at the flank face increase with decreasing micro topography. In contrast, no general conclusions can be drawn regarding the influence of coating micro topography on the contact conditions at the rake face. The resulting topography of the turned surface was found to increase with increasing coating topography.

  • 46.
    Hall, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Beglund, Tomas
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Influence of microstructure and hard phase content on the mechanisms of deformation and wear of HIP:ed Stellite® 190 composites2015Conference paper (Refereed)
  • 47.
    Hall, Josefine
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Berglund, Tomas
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Influence of Microstructure and Hard Phase Content on the Mechanisms of Deformation and Wear of HIP:ed Stellite® 190 Composites2015In: Proceedings of 2015 European powder metallurgy congress, Euro PM 2015, Reims, France, 4-7 October 2015, 2015Conference paper (Refereed)
  • 48. Harlin, P.
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Starch consolidation of M3/2 high speed steel powder: Influence of microstructure on mechanical properties2007In: Powder Metallurgy, ISSN 0032-5899, E-ISSN 1743-2901, Vol. 50, no 3, 232-238 p.Article in journal (Refereed)
    Abstract [en]

    The influence of microstructure on the mechanical properties of starch consolidated super solidus liquid phase sintered AISI type M3/2 high speed steel powder has been evaluated. Hardness measurements, Rockwell C indentation and scratch testing were used to evaluate the mechanical properties and light optical microscopy and scanning electron microscopy were used for post-test characterisation. The results show that it is possible to starch consolidate and sinter large particle size high speed steel powder to obtain microstructures with high mechanical strength. However, the results show a strong correlation between the as sintered microstructure and the resulting mechanical properties and illuminate the importance of having a dense and isotropic microstructure in order to meet engineering requirements in demanding applications. Consequently, the failure mechanisms observed during indentation and scratch testing can be related to residual pores, present in the low temperature sintered samples, and a coarse microstructure with eutectic carbides, present in the high temperature sintered samples. 

  • 49.
    Harlin, Peter
    et al.
    Sandvik Materials Technology.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    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 conditions2009In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 203, no 13, 1748-1755 p.Article in journal (Refereed)
    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.

  • 50.
    Harlin, Peter
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Influence of surface roughness of PVD coatings on tribological performance in sliding contacts2006In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 201, no 7, 4253-4259 p.Article in journal (Refereed)
    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.

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