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  • 1.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of contact parameters on material transfer from steel to TiN coated tool: optimisation of a sliding test for simulation of material transfer in milling2016In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 10, no 3, p. 107-116Article in journal (Refereed)
    Abstract [en]

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

  • 2.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of combined additions of Si, Mn, Cr and Al to carbon steel on material transfer in a steel/TiN coated tool sliding contact2017In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 388-389, p. 9-17Article in journal (Refereed)
    Abstract [en]

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

  • 3.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of Si and Al additions to carbon steel on material transfer and coating damage mechanism in turning with CVD coated tools2016In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 368-369, p. 379-389Article in journal (Refereed)
    Abstract [en]

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

  • 4.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of Si and Cr additions to carbon steel on material transfer in a steel/TiN coated tool sliding contact2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 97, p. 337-348Article in journal (Refereed)
    Abstract [en]

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

  • 5.
    Aiso, Toshiharu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of Mn and Al additions to carbon steel on material transfer and coating damage mechanism in a sliding contact between steel and TiN coated HSS tool2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 101, p. 414-424Article in journal (Refereed)
    Abstract [en]

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

  • 6.
    Andre, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hollman, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanoindentation on micro pillars for determination of intrinsic hardness and residual stress in coatings deposited on complex geometries2012In: Tribologia, ISSN 0780-2285, Vol. 31, no 1-2, p. 22-31Article in journal (Refereed)
    Abstract [en]

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

  • 7.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hollman, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanoindentation on micro pillars for determination of intrincic hardness and residual stress in coatings deposited on complex geometriesManuscript (preprint) (Other academic)
  • 8.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction and contact resistance of nanocomposite Ti-Ni-C coatings2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, no 9-10, p. 555-566Article in journal (Refereed)
    Abstract [en]

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

  • 9.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Lindquist, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribological testing of ceramic coatings boosted for low friction and for use in electrical contacts2008Conference paper (Refereed)
  • 10.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction and wear dependence of nc-TiNiC:a-C by environment and test conditions2010Conference paper (Refereed)
  • 11.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanoindentation on micro pillars for determination of residual stress conditions of PVD coatings2011Conference paper (Refereed)
  • 12.
    Berger, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, U
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Eriksson, M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, H
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The multilayer effect in abrasion: optimising the combination of hard and tough phases1999In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 116-119, p. 1138-1144Article in journal (Other academic)
    Abstract [en]

    In the present investigation it is shown that the wear resistance of multilayer PVD coatings, combining relatively soft but tough chromium (Cr) and harder but more brittle chromium nitride (CrN): exceeds that of both its phases. This striking exception to

  • 13.
    Carlsson, Jenny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Heldin, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Isaksson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Investigating tool engagement in groundwood pulping: finite element modelling and in-situ observations at the microscale2020In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 74, no 5, p. 477-487Article in journal (Refereed)
    Abstract [en]

    With industrial groundwood pulping processes relying on carefully designed grit surfaces being developed for commercial use, it is increasingly important to understand the mechanisms occurring in the contact between wood and tool. We present a methodology to experimentally and numerically analyse the effect of different tool geometries on the groundwood pulping defibration process. Using a combination of high-resolution experimental and numerical methods, including finite element (FE) models, digital volume correlation (DVC) of synchrotron radiation-based X-ray computed tomography (CT) of initial grinding and lab-scale grinding experiments, this paper aims to study such mechanisms. Three different asperity geometries were studied in FE simulations and in grinding of wood from Norway spruce. We found a good correlation between strains obtained from FE models and strains calculated using DVC from stacks of CT images of initial grinding. We also correlate the strains obtained from numerical models to the integrity of the separated fibres in lab-scale grinding experiments. In conclusion, we found that, by modifying the asperity geometries, it is, to some extent, possible to control the underlying mechanisms, enabling development of better tools in terms of efficiency, quality of the fibres and stability of the groundwood pulping process.

  • 14.
    Carlsson, Mattias
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science.
    Wiklund, Urban
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Materials Science.
    A comparative evaluation method for low friction coatings in dry sliding thrust bearings2004In: Tribologia, Vol. 23, no 3-4, p. 27-36Article in journal (Refereed)
  • 15. Casas, B.
    et al.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lanes, L.M.
    Hogmark, Sture
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion and abrasive wear resistance of TiN deposited on electrical discharge machined WC-Co cements rbides2008In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 265, no 3-4, p. 490-496Article in journal (Refereed)
    Abstract [en]

    Electrical discharge machining (EDM) is a non-traditional machining method extensively used to manufacture complex geometries of hard and brittle materials such as WC-Co cemented carbides (CC). Although the thermal action of the EDM process is known to yield a relatively poor surface integrity in these materials, it may be minimized through the implementation of multi-step sequential EDM and post-EDM surface treatments. Particularly, hard coating application has been demonstrated to be effective for decreasing the EDM-induced mechanical degradation. However, additional studies are required on such coating-EDMed substrate systems to determine other crucial properties in terms of applications, e.g. adhesion and micro-scale wear behaviour. In this work the adhesion strength and the microabrasive wear resistance of TiN deposited on EDMed substrates have been evaluated by means of scratch and crater grinder testing, respectively. The results indicate that both critical load for decohesion of the coating from the substrate and coating specific wear rate increase with finer-executed EDM, reaching values close to those measured for a TiN coating deposited on a ground and polished substrate.

  • 16.
    Coronel, E
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olsson, E
    The effect of carbon content on the microstructure of hydrogen-free physical vapour deposited titanium carbide films2009In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, no 1, p. 71-76Article in journal (Refereed)
    Abstract [en]

    Titanium carbide (TiC) coatings for tribological applications were deposited on high speed steel. Several coatings with different titanium to carbon ratio were deposited by means of physical vapour deposition in which titanium was evaporated and carbon was sputtered. The coatings were characterised using analytical electron microscopy. It was observed that the change in titanium to carbon ratio significantly changed the microstructure of the coatings. The low carbon containing coatings consisted of columnar grains exhibiting a preferred crystallographic orientation whereas the coating with highest carbon content consisted of randomly ordered TiC grains in an amorphous carbon matrix. Energy filtered transmission electron microscopy revealed a change in Ti/C ratio as the distance from the substrate increased. The titanium to carbon ratio was observed to increase with distance from the substrate until a stable level was reached. This is due to a variation in the titanium evaporation during the early stages of film growth. This change of the titanium to carbon ratio affected the columnar growth in the initial stage of coating growth for the coatings with low carbon content.

  • 17.
    Crossley, A
    et al.
    AEA Technology, UK.
    Johnston, C
    Hutchings, I M
    Myhra, S
    Temple, J A G
    Wiklund, U
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Surface treatment for galling protection of titanium alloys: characterization by surface-specific electron and Raman spectroscopies2002In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 414, no 2, p. 224-230Article in journal (Refereed)
  • 18.
    Engqvist, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mapping of mechanical properties of WC-Co using nanoindentation2000In: Tribology letters, ISSN 1023-8883, Vol. 8, no 2-3, p. 147-152Article in journal (Refereed)
    Abstract [en]

    High-resolution measurements of mechanical properties are of immense importance in metallurgy. Measuring the intrinsic properties of each phase separately in multiphase materials gives information that is valuable for the development of new materials and

  • 19.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Collin, Marianne
    Sandvik Machining Solutions, Stockholm.
    Andersson, Gunilla
    Sandvik Machining Solutions, Stockholm.
    Nordh, Lars-Göran
    Uddeholms AB, Hagfors.
    Heinrichs, Jannica
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion phenomena in the secondary shear zone in turning of austenitic stainless steel and carbon steel2012Conference paper (Other academic)
  • 20.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gustavsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Collin, Marianne
    Sandvik Machining Solutions, Stockholm.
    Gunilla, Andersson
    Sandvik Machining Solutions, Stockholm.
    Lars-Göran, Nordh
    Uddeholms AB, Hagfors.
    Heinrichs, Jannica
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion phenomena in the secondary shear zone in turning of austenitic stainless steel and carbon steel2014In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 214, no 8, p. 1467-1481Article in journal (Refereed)
    Abstract [en]

    This paper aims to increase the understanding of the adhesion between chip and tool rake face by studying the initial material transfer to the tool during orthogonal machining at 150 m/min. Two types of work material were tested, an austenitic stainless steel, 316L, and a carbon steel, UHB 11. The tools used were cemented carbide inserts coated with hard ceramic coatings. Two different CVD coatings, TiN and Al2O3, produced with two different surface roughnesses, polished and rough, were tested. The influences of both tool surface topography and chemistry on the adhesion phenomena in the secondary shear zone were thus evaluated. Extensive surface analyses of the inserts after cutting were made using techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM). As expected, cutting in the stainless steel resulted in a higher amount of adhered material, compared to cutting in the carbon steel. Remnants of built-up layers were found on the surfaces of the 316L chips but not on the UHB 11 chips. Moreover, it was shown that for both materials the tool roughness had a profound effect, with the rougher surfaces comprising much higher amounts of adhered material than the polished ones. Non-metallic inclusions from both types of workpiece steels accumulate in the high temperature area on the inserts. The general tendency was that higher amounts of transferred material were found on the TiN coating than on the Al2O3 coating after cutting.

  • 21.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Heinrichs, Jannica
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nyberg, Harald
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Larsson, Mats
    Primateria AB, Uppsala.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Evaluation of an intermittent sliding test for reproducing work material transfer in milling operations2012In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 52, p. 153-160Article in journal (Refereed)
    Abstract [en]

    TiN coated HSS test cylinders from an intermittent sliding test were compared with TiN coated HSS milling inserts from a single insert milling test. A 20NiCrMo2 case hardening steel was used as counter material and work material in the two tests. HSS test cylinders, coated with AlCrN, TiAlN and Al2O3, were also tested in the intermittent sliding test and evaluated with regard to material adhesion. Two distinctly different tribofilms were formed on test cylinders as well as on cutting inserts. One consisting of Mn, Si, Al and O and one consisting of Fe, Mn, Cr, Si and O. The transferred material was similar in appearance and composition, both when comparing the two test methods and when comparing the different tool coatings.

  • 22.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Larsson, Mats
    Urban, Wiklund
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Survey of damage mechanisms on PVD coated HSS hobs used in Swedish gear manufacturing industry2011In: Tribologia, ISSN 0780-2285, Vol. 30, no 1-2, p. 37-50Article in journal (Refereed)
    Abstract [en]

    Gear hobbing is widely used for production of cylindrical gears in the Swedish transmission industry. The hob, usually consisting of a homogenous HSS (High Speed Steel) body coated with a ceramic PVD (Physical Vapour Deposition) coating, is designed for regrinding and recoating several times without affecting its cutting geometries. Efficient usage of the tool, considering production costs and gear quality, requires reconditioning before wear starts to affect the gear quality negatively and certainly before tool wear renders reconditioning impossible. Hobs of today generally lack in reliability, making it difficult to judge when they have to be taken out for reconditioning.

     

    This work presents a survey of wear as observed on today’s state of the art hobs used by Swedish gear manufactures. It aims to identify damage mechanisms and the common problems in order to enable future production of more reliable hobs. The tools were temporarily borrowed from the production and the analyses were made non-destructively using optical microscopes. This was complemented by destructive cross-sectional analysis on two of the hobs.

     

    Wear was most commonly located on the rake faces and the cutting edges of the cutting teeth. It mainly propagates by discrete fractures which appear to originate at local defects in the coating or at the interface. High intrinsic stress in the coating likely promotes coating spallation and accelerates the wear of the cutting edge.

  • 23.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Larsson, Mats
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wear propagation of PVD AlCrN coated HSS hob in dry gear hobbing2007Conference paper (Refereed)
  • 24.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Larsson, Mats
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Riddar, Frida
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hogmark, Sture
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    On the wear of PVD-coated HSS hobs in dry gear cutting2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, no 3-4, p. 444-452Article in journal (Refereed)
    Abstract [en]

    A hob is an advanced gear cutting tool usually made of homogenous high-speed steel (HSS) and coated by physical vapour deposition (PVD). It is designed for regrinding and recoating many times. However, hobs of today suffer from unpredictable wear making it difficult to schedule when they should be taken out for reconditioning. This investigation is aimed to contribute to the fundamental knowledge of the wear mechanisms and wear propagation of hobs used in dry gear cutting. Two AlCrN-coated hobs, used in actual gear cutting, were investigated by scanning electron microscopy (SEM) to study the tool topography, light optical microscopy (LOM) to study metallographic cross-sections and by X-ray photoelectron spectroscopy (XPS) for surface analyses.

    It is concluded that the high potential of PVD-coated HSS as tool material is not taken full advantage of. The main reason is a combination of a poor surface preparation prior to coating and excessively high compressive residual stresses, making parts of the coating detach along the edge line even on unused cutting teeth. During cutting, the high intrinsic stresses in combination with droplets and defects in the coating facilitated its fragmentation through decohesion and detachment. Simultaneously, the rake face is gradually covered by a thin oxide layer dominated by Fe, Cr and Mn in about equal amounts, and also with a significant content of Si. It is believed but not proved that this layer is beneficial.

    To improve service life and reliability of gear cutting hobs, precautions should be taken for the grinding–polishing preparation prior to PVD-coating to ensure a smooth substrate free from burning damage and other defects. Also, the edge radius and coating thickness has to be matched with the magnitude of compressive residual stresses in the coating.

  • 25.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Werner, Mathias
    KTH.
    Larsson, Mats
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Reproducing wear mechanisms in gear hobbing: evaluation of a single insert milling test2008In: Proceedings of the International conference Nordtrib 2008, 2008Conference paper (Refereed)
  • 26.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Werner, Mathias
    KTH.
    Larsson, Mats
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Reproducing wear mechanisms in gear hobbing: Evaluation of a single insert milling test2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, no 12, p. 2257-2268Article in journal (Refereed)
    Abstract [en]

    Gear hobbing is a widely used method in industrial gear manufacturing. The most common type of hob is made of homogenous HSS and protected by a PVD coating. In order to increase the reliability and tool life of these milling tools, further developments of the tool surfaces and cutting edges are necessary.

    A single tooth milling test, using a HSS insert in a conventional milling machine, has been developed with the aim to reproduce the wear mechanisms seen on real HSS gear hobbing teeth. The benefits of such a test, compared to actual gear hobbing tests, are primarily accessibility and reduced costs for both design and production of test specimens (inserts).

    The main goal of this study was to verify that the wear mechanisms in the developed test correspond with the wear mechanisms obtained in real gear hobbing. Once this was verified, the influence of surfaces roughness on the performance of TiAlN coated HSS inserts was evaluated by using the tool as delivered or after polishing the tool surfaces. Parameters considered were tool wear, cutting forces and the quality of machined surfaces. The polished inserts, yielded less adhered work material and reduced flank wear but no significant difference in cutting forces as compared to the unpolished inserts.

  • 27.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Adhesion properties in the secondary shear zone in turning of austenitic stainless steel and carbon steel2012Conference paper (Refereed)
  • 28.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The influence of metallic interlayers on the adhesion of pVD TiN coatings on high-speed steel2007In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, no 9-10, p. 885-892Article in journal (Refereed)
    Abstract [en]

    In nearly all applications the adhesion of the coating to the substrate is crucial for the components performance and length of life. To enhance the adhesion it is common to use a metallic interlayer, most often titanium. In this study seven different metallic interlayers, namely W, Mo, Nb, Cr, Ti, Ag and Al, have been evaluated with respect to their influence on the adhesion of PVD TiN coatings to polished high-speed steel, ASP 2060. The purpose of this work is to investigate how some physical properties of a metal affect its capability to function as an adhesion interlayer. Samples were prepared using dc magnetron sputtering for the interlayer and reactive dc magnetron sputtering for the TiN coating. The deposition process included both pre-treatments and in situ treatments of the substrate surface in order to eliminate possible contaminations. The adhesion of the coatings was investigated with two different methods: scratch testing and Rockwell adhesion testing. The results indicate that differences in hardness between the metallic interlayers influence the practical adhesion more than differences in E-modulus. Furthermore, in order to optimize adhesion, the hardness of the interlayer should be close to the hardness of the substrate. It was also suggested that stresses, both in the TiN coating and in the metallic interlayer, affect the adhesion properties negatively. In addition, the necessity of interlayer in TiN on HSS can be questioned as the reference samples, without interlayer, showed adhesion properties comparable to the highest ranked interlayer containing samples in our assessment.

  • 29.
    Gerth, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wear of an AlCrN coated HSS Hob in Dry Gear Cutting2009In: HSS FORUM - Smart Solutions for the Future of Metal Cutting, 2009Conference paper (Refereed)
  • 30.
    Goel, S.
    et al.
    Univ West, Dept Engn Sci, S-46186 Trollhattan, Sweden..
    Bjorklund, S.
    Univ West, Dept Engn Sci, S-46186 Trollhattan, Sweden..
    Curry, N.
    Treibacher Ind AG, Althofen, Austria..
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Joshi, S. V.
    Univ West, Dept Engn Sci, S-46186 Trollhattan, Sweden..
    Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 315, p. 80-87Article in journal (Refereed)
    Abstract [en]

    Suspension plasma spray is a relatively new thermal spray technique which enables feeding of fine powder to produce advanced coatings for varied applications. This work investigates the difference in structure and performance of Al2O3 coatings manufactured using conventional micron-sized powder feedstock and a suspension of sub-micron to few micron sized powder. Axial injection was implemented for deposition in both cases. The effect of feedstock size and processing on the tribological performance of the two coatings was of specific interest. The coatings were characterized by Optical and Scanning Electron Microscopy, micro-hardness and scratch resistance testing, and their dry sliding wear performance evaluated. The suspension sprayed coatings yielded significantly higher scratch resistance, lower friction coefficient and reduced wear rate compared to conventional coatings. The improved tribological behaviour of the former is attributable to finer porosity, smaller splat sizes, and improved interlamellar bonding.

  • 31.
    Goel, Sneha
    et al.
    Univ West, Dept Engn Sci, S-46132 Trollhättan, Sweden..
    Bjorklund, Stefan
    Univ West, Dept Engn Sci, S-46132 Trollhättan, Sweden..
    Curry, Nicholas
    Treibacher Ind AG, A-9330 Althofen, Austria..
    Govindarajan, Sivakumar
    Int Adv Res Ctr Powder Met & New Mat, Hyderabad 500005, India..
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Gaudiuso, Caterina
    Univ Bari, Phys Dept, Via Amendola 173, I-70126 Bari, Italy..
    Joshi, Shrikant
    Univ West, Dept Engn Sci, S-46132 Trollhättan, Sweden..
    Axial Plasma Spraying of Mixed Suspensions: A Case Study on Processing, Characteristics, and Tribological Behavior of Al2O3-YSZ Coatings2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 15, article id 5140Article in journal (Refereed)
    Abstract [en]

    Thermal spraying deploying liquid feedstock offers an exciting opportunity to obtain coatings with characteristics vastly different from those produced using conventional spray-grade powders. The most extensively investigated variant of this technique is Suspension Plasma Spraying (SPS), which utilizes a suspension of fine powders in an appropriate medium. The relatively recent advent of axial feed capable plasma spray systems can enable higher throughputs during SPS, provides the possibility for spraying with longer stand-off distances, and also permit the use of suspensions with higher solid loading. The present work investigates axial plasma sprayed coatings produced using a mixed suspension of fine (submicron or nano-sized) powders of Al(2)O(3)and YSZ as a case study. Deposition of the mixed suspension using axial injection plasma spraying, comprehensive evaluation of characteristics of the resulting coatings, and assessment of their tribological behavior were of particular interest. Evaluation of surface morphology, microstructure, and hardness of the coatings reveals that axial SPS of mixed suspensions provides an exciting pathway to realize finely structured multi-constituent coatings using suspensions with as high as 40 wt.% solid loading. The study of scratch, dry sliding wear, and erosion behavior also specifically shows that the addition of YSZ in the Al(2)O(3)matrix can improve the tribological properties of the coating.

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  • 32.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nedfors, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sundberg, Jill
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ti-Ni-C nanocomposite coatings evaluated in a sliding electrical contact application2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 276, p. 210-218Article in journal (Refereed)
    Abstract [en]

    Nanocomposite Ti-Ni-C coatings, with nanosized carbide grains in an amorphous carbon (a-C) matrix have been suggested to have low friction and low contact resistance making them suitable for sliding electrical contacts. In this study we investigate further the previously observed influence of the amount of amorphous carbon, in a test set-up simulating instrumentation and control applications. The tribological and electrical performance is evaluated at high speed and continuous sliding against silver-graphite, where the mechanical load and current are fairly low. It is shown that under these circumstances there is no significant influence from the amount of a-C on neither the contact resistance nor the amount of wear of the silver-graphite. The reason for this is suggested to be that similar tribofilms are formed on the surface of the coatings, regardless of the amount of a-C phase. Degradation of the nanocomposite coatings is observed under electrical load, even though they are both much harder than the silver-graphite counter surface.

  • 33.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    A wear tolerant slip-ring assembly, individual spring-wire brushes in a v-grooved metal-graphite ring2014In: Proceedings of the 27th International Conference on Electrical Contacts, VDE Verlag GMBH Berlin Offenbach , 2014, p. 237-243Conference paper (Refereed)
  • 34.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction, wear and tribofilm formation on electrical contact materials in reciprocating sliding against silver-graphite2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 302, no 1-2 SI, p. 1481-1491Article in journal (Refereed)
    Abstract [en]

    In this study nanocomposite coatings mating silver-graphite were investigated for sliding electrical contact applications with the aim to optimize tribological and electrical properties. Apart from two different Ti–Ni–C nanocomposite coatings, brass, steel and TiN were also tested against a commercial silver-graphite at varying load and current. Friction, wear and contact resistance were measured in reciprocating sliding in ambient air. It was concluded that the wear of the silver-graphite was increased by current, for TiN and steel as much as four times, at a 5 N load. A tribofilm, with properties differing from the silver-graphite, formed on the coating/metal surface in all cases. This resulted in a very similar coefficient of friction, 0.3, for all mating materials. However, different load and current gave rise to slightly different thickness and morphology. A too low load was detrimental, as the coating became damaged, while a too high load was not favorable for tribofilm formation. In tests with varying current, a specific current could be identified that best governed the build-up of a well conducting and stable tribofilm. The largest differences were observed in the initial stages of testing, since once the tribofilm was built up, the contact resistance approached that of self mated silver-graphite, 40 mΩ. Experiments showed that the load and the current can be optimized to minimize wear of the silver-graphite which in turn would allow for lower maintenance costs.

  • 35.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction, wear and tribofilm formation on electrical contact materials in reciprocating sliding against silver-graphite2013Conference paper (Refereed)
  • 36.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of mechanical and electrical load on a copper/copper-graphite sliding electrical contact2018In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 121, p. 1-9Article in journal (Refereed)
    Abstract [en]

    For sliding electrical contacts a combination of satisfactory current transfer and good tribological performance is desired. A complete tribo-electrical study is presented where a mechanical and an electrical load are applied and tribological and electrical properties are evaluated. Stationary copper plated spring steel wires are tested against rotating copper-graphite rings at varying mechanical and electrical load. The focus is on surface modifications of the copper and correlations to the electrical performance are discussed. It is concluded that the tribological action is dominating over any influence from current, resulting in a mechanically mixed layer of Cu20 and Cu, for all currents as well as for the pure mechanical case. A graphitic layer is observed on the very surface of the wire.

  • 37.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wear and electrical performance of a slip-ring system with silver-graphite in continuous sliding against PVD coated wires2016In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 348, p. 138-147Article in journal (Refereed)
    Abstract [en]

    Sliding electrical contacts transferring current between stationary and rotating components are also tribological systems. Although low contact resistance and noise are prioritised, lower wear rates reduce material usage, and lower friction reduce energy loss. In this paper a slip-ring assembly with wires contacting a silver-graphite ring is investigated with the aim to optimize the wire material to displace all wear to the ring. Uncoated wires and wires coated with nanocomposite Ti-Ni-C or TiN are tested at 100 mA current. Tribofilms, consisting mainly of silver and carbon, form on the wires and a contact resistance of around 0.5 Omega is measured for all wire materials. The properties of the tribofilms control the overall performance and the similarity between them, regardless of wire material, is the reason for the similar contact resistance. The Ti-Ni-C coating wear least on the silver-graphite. Both coatings degrade and wear off during testing, exposing the steel substrate. The steel itself also wears, although not at a rate excluding it as a possible wire material. None of the three surfaces fully displaces wear to the ring only. Considering the performance of the uncoated steel wire, coatings cannot be motivated on behalf of either improved electrical performance or wire protection.

  • 38.
    Grandin, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wear phenomena and tribofilm formation of copper/copper-graphite sliding electrical contact materials2018In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 398-399, p. 227-235Article in journal (Refereed)
    Abstract [en]

    Copper-graphite composites of different compositions sliding against copper are investigated with regards to friction, wear and contact resistance. We find that comprehensive studies including the tribological as well as electrical aspects are rarely found in the literature. We combine friction, wear and contact resistance measurements with thorough surface analysis to complete the understanding. We find that including graphite in the composite greatly reduce the coefficient of friction. However, increasing the vol.% of graphite above 74 will not continue to reduce the friction. We conclude that the coefficient of friction is slightly lower when testing is performed without current than at 5 A current. A comparison of the specific wear rate for the tested composites shows that the one with 74 vol.% of graphite gives the lowest wear rate. In general, the wear rate is higher when tests are performed without current. Chemical analysis of the tribofilm that forms on the copper surface shows that it consists of graphite as well as Cu2O. It is also shown that the amount of graphite in the tribofilm correlates to the composition of the copper-graphite. Novel cross-section images of the tribofilm contribute to a deeper understanding of how sliding electrical contact surfaces are affected by current and sliding motion.

  • 39.
    Gunnars, J
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Wiklund, U
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Determination of growth-induced strain and thermoelastic properties of coatings by curvature measurements2002In: Materials Science and Engineering A, ISSN 0921-5093, Vol. 336, no 1-2, p. 7-21Article in journal (Refereed)
  • 40.
    Hassila, Carl Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Harlin, P.
    Sandvik Mat Technol AB, Sandviken, Sweden.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Rolling contact fatigue crack propagation relative to anisotropies in additive manufactured Inconel 6252019In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 426-427, no Part B, p. 1837-1845Article in journal (Refereed)
    Abstract [en]

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

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  • 41.
    Hassila, Carl Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Harlin, Peter
    Sandvik AB.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala University.
    Influence of Nitrogen Content on Microstructure and Mechanical Properties of Laser Powder Bed Fusion Processed Alloy 6252020In: World PM 2020, 27/6-1/7 2020, Montreal, Kanada, 2020Conference paper (Refereed)
    Abstract [en]

    Alloy 625 is a nickel-based alloy used for high temperature applications and corrosive environments. The compositional specification of alloy 625 is quite wide, which makes it possible to tune the alloy composition to allow for a higher nitrogen content. In this study we investigate two such tuned 625 powders having different nitrogen contents and how their respective nitrogen contents effect the properties of the fused material after processing in laser powder bed fusion. The microstructural characteristics and the mechanical performance of the fused materials were evaluated both in the as-built material condition and after hot isostatic pressing (HIP). The mechanical evaluation includes tensile and impact testing as well as Vickers indentation. Results from microstructural characterisation displays small variations in the as-built condition whilst the alloys have a significantly different response on the performed HIP cycle. The variations in microstructure after HIP has also a direct impact on resulting mechanical properties.

  • 42. Hassila, C.J.
    et al.
    Paschalidou, Eirini-Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Harlin, P.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Potential of nitrogen atomized alloy 625 in the powder bed fusion laser beam process2022In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 221, p. 110928-110928, article id 110928Article in journal (Refereed)
    Abstract [en]

    Powder based metal additive manufacturing processes like Powder Bed Fusion – Laser Beam utilize gasatomized metal powders as feedstock material. Typically, for nickel-based alloys such as Alloy 625, argongas is used during the atomization process. Considering the larger environmental impact of argon gascompared to nitrogen gas, and the increasing use of gas atomized metal powders, the environmentalimpact of powder based additive manufacturing techniques could be mitigated if gas atomization ofalloys such as Alloy 625 using nitrogen was possible. This work investigates the feasibility of tailoringan alloy to allow atomization using nitrogen gas while remaining within the Alloy 625 specification.This is achieved by limiting the nitrogen pick-up during the atomization process, primarily by reducingthe titanium content. The metallurgical implications of this tailored alloy and the subsequent atomizationusing nitrogen, as well as the attained microstructure from the Powder Bed Fusion – Laser Beam processis investigated and compared to a more common 625 alloy composition which was atomized usingargon. Furthermore, the microstructural development of the alloys after heat treatments are evaluated.Lastly corrosive properties, as well as tensile and impact properties are evaluated both in the as-builtand hot isostatic pressed condition.

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  • 43.
    Hassila Karlsson, Carl Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Harlin, Peter
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Influence of carbon content on microstructure and mechanical properties of Inconel 718 processed with Powder Bed Fusion – Laser BeamManuscript (preprint) (Other academic)
    Abstract [en]

    Additive manufacturing of alloys belonging to the Inconel family is today a hot research topic. Given that these alloys were developed with casting and forging as the main manufacturing route, the possibilities of adjusting their composition to make them better suited for the additive manufacturing processes should be investigated. In this work we study two different versions of Alloy 718 with different carbon content; one having a normal carbon content and one having a very low carbon content. Test pieces from these alloys were produced using the Powder Bed Fusion – Laser Beam process. TEM and SEM with EDS/EBSD was used to study the resulting microstructures both in the as-built and after heat treatment. Mechanical properties were evaluated for samples printed in different build directions using tensile and impact testing. The achieved materials in the as-built condition were very similar to one another in both the microstructure and the displayed mechanical properties. After heat treatment, differences in the microstructures could be identified as secondary carbides were found to precipitate exclusively in the alloy with a normal carbon content. Additionally, the different carbon contents affected the number of annealing twins that formed in the respective alloys, where more twins formed in the alloy with a low carbon content. This was attributed to the alloy’s lower stacking-fault energy. As annealing twins facilitate the transformation of the anisotropic as-built grain structure, effectively making the materials more isotropic, only the low carbon content alloy showed isotropic material properties after heat treatment. 

  • 44.
    Hassila Karlsson, Carl Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Malmelöv, Andreas
    Andersson, Carl
    Hektor, Johan
    Fisk, Martin
    Lundbäck, Andreas
    Wiklund, Urban
    Influence of scanning strategy on residual stresses in laser powder bed fusion manufactured alloy 718: Modeling and experimentsManuscript (preprint) (Other academic)
    Abstract [en]

    Residual stresses are a known phenomenon in additively manufactured materials. The residual stresses increase the risk of cracks, limit in-service performance, and distort printed parts. In this work, thermo-mechanical finite element models using the hatch-by-hatch and layer-by-layer approach, and the inherent strain method has been developed and applied to predict the effects of different scanning strategies on the deflection and the residual stresses of two PBF-LB processed geometries. To account for viscoplasticty and relaxation effects, a mechanism-based material model have been implemented and used. It is shown that the hatch-by-hatch approach and inherent strain method both successfully predicted the experimentally measured deflections of the first geometry, which was printed using different scanning directions. To predict the stress field experimentally, high-energy synchrotron measurements have been used to. The thermo-mechanical models and the inherent strain method both captures the trend of experimentally measured residual stress fields, although with an overall underprediction. The predictions of the models were evaluated, and their accuracy discussed in terms of physical aspects of the Powder Bed Fusion – Laser Beam process.

  • 45.
    Hassila Karlsson, Carl Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Rolling contact fatigue test performed on additively manufactured inconel 718 produced by selective laser melting2018In: 18th Nordic Symposium on Tribology - NORDTRIB 2018, Uppsala, Sweden, June 18-21, 2018, Uppsala, 2018Conference paper (Refereed)
    Abstract [en]

    Powder bed additive manufacturing (AM) is a method for producing near-net-shape components by selectively melting metal powder where material is desired, layer by later. This is directly contrary to conventional machining being a solely subtractive process where material is removed from a large work piece. It is well known that AM often results in microstructural anisotropy related to the build direction. In the case of Inconel 718, columnar grains are formed, oriented along the build direction. Furthermore, utilizing different scan strategies such as contouring will result in different grain structures in the near surface region compared to the bulk of the material. The aim of this work was to study the effects of these microstructural anisotropies on the mechanical and tribological properties. Cylindrical test specimens with were built with different build directions and scan strategies and mechanically characterized and tested in a rolling contact fatigue test rig where a specimen was placed between two hard rollers. As the very surface presents a rough topography comprised of partly melted powder particles which hinders any tribological function of the component the samples were grinded prior to the rolling contact fatigue tests. After testing, the contact tracks were analyzed using, SEM and EBSD.

  • 46.
    Heinrichs, Jannica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gerth, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bexell, Ulf
    Dalarna University.
    Larsson, Mats
    Primateria AB, Uppsala.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence from surface roughness on steel transfer to PVD tool coatings in continuous and intermittent sliding contacts2012In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 56, p. 9-18Article in journal (Refereed)
    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.

  • 47.
    Heinrichs, Jannica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gerth, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thersleff, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bexell, Ulf
    Dalarna University.
    Larsson, Mats
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence of sliding speed on modes of material transfer as steel slides against PVD tool coatings2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 58, p. 55-64Article in journal (Refereed)
    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.

  • 48.
    Heinrichs, Jannica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jarmar, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Physical vapour deposition and bioactivity of crystalline titanium dioxide thin films2008In: Trends in Biomaterials & Artificial Organs, ISSN 0971-1198, Vol. 22, no 2, p. 104-110Article in journal (Refereed)
  • 49.
    Heinrichs, Jannica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kawakami, Ayumi
    YKK Corporation, Japan.
    Mikado, Hiroko
    YKK Corporation, Japan.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kawamura, Shingo
    YKK Corporation, Japan.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wear mechanisms of WC-Co cemented carbide tools and PVD coated tools used for shearing Cu-alloy wire2018Conference paper (Other academic)
  • 50.
    Heinrichs, Jannica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Mikado, H.
    YKK Corp, Technol & Innovat Ctr, Tokyo, Japan..
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Surreddi, K. B.
    Dalarna Univ, Sch Informat & Engn, Mat Technol, Falun, Sweden..
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Kawamura, S.
    YKK Corp, Technol & Innovat Ctr, Tokyo, Japan..
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Exploring the tribochemical wear and material transfer caused by Cu15Zn alloys on shearing tools2024In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 542, article id 205274Article in journal (Refereed)
    Abstract [en]

    Cemented carbide tools are extensively used in the zipper industry, including shearing of a pre-formed Cu15Zn wire into individual zipper elements. Although the work material is significantly softer than the tool, wear is the life limiting factor for the tools and is considered to be of tribochemical nature. So far it has not been explained, however, it is known that the wear rate of uncoated, as well as CrC and CrN coated, cemented carbide increases dramatically when Zn is omitted from the Cu alloy. In this paper, worn tool surfaces, including any transferred material, were studied to investigate the tribochemical wear mechanism in detail. Material transfer occurred onto all tool surfaces. Cu and Zn were separated on the sub-micron scale, and preferential transfer of one of the constituents was observed. This is reflected in the outermost surface of the sheared element, which shows a homogeneous composition elsewhere. Oxidation was observed of all tool surfaces, which indicates elements of oxidative wear. Further, any Zn transferred to the tool surfaces was oxidized. Thus, it is suggested that the presence of Zn reduces the oxygen available and consequently reduces the oxidation rate of the tool surfaces, leading to the protective effect previously observed.

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