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  • 1. Abbasi, Saeed
    et al.
    Jansson, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Olander, Lars
    Olofsson, Ulf
    Sellgren, Ulf
    A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials2012Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 284, s. 18-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm-32 mu m in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

  • 2.
    Abbasi, Saeed
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Jansson, Anders
    Stockholm University, Applied Environmental Science, Stockholm, Sweden.
    Olander, Lars
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Installationsteknik.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials2012Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 284, s. 18-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm-32 mu m in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

  • 3.
    Abbasi, Saeed
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. Department of Mechanical engineering, Golpayegan University of Technology.
    Teimourimanesh, Shahab
    Chalmers.
    Vernersson, Tore
    Chalmers.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Lunden, Roger
    Chalmers.
    Temperature and Thermoelastic Instability at Tread Braking Using Cast Iron Friction Material2013Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 314, nr 1–2, s. 171-180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Braking events in railway traffic often induce high frictional heating and thermoelastic instability (TEI) at the interfacing surfaces. In the present paper, two approaches are adopted to analyse the thermomechanical interaction in a pin-on-disc experimental study of railway braking materials. In a first part, the thermal problem is studied to find the heat partitioning between pin and disc motivated by the fact that wear mechanisms can be explained with a better understanding of the prevailing thermal conditions. The numerical model is calibrated using the experimental results. In a second part, the frictionally induced thermoelastic instabilities at the pin-disc contact are studied using a numerical method and comparing them with the phenomena observed in the experiments. The effects of temperature on material properties and on material wear are considered. It is found from the thermal analysis that the pin temperature and the heat flux to the pin increase with increasing disc temperatures up to a transition stage. This agrees with the behaviour found in the experiments. Furthermore, the thermoelastic analysis displays calculated pressure and the temperature distributions at the contact interface that are in agreement with the hot spot behaviour observed in the experiments.

  • 4.
    Abbasi, Saeed
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Wahlström, Jens
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olander, Lars
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Installationsteknik.
    Larsson, Christina
    Bombardier Transportation Sweden AB, Västerås, Sweden.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    A study of airborne wear particles generated from organic railway brake pads and brake discs2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, nr 1, s. 93-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Brake pads on wheel-mounted disc brakes are often used in rail transport due to their good thermal properties and robustness. During braking, both the disc and the pads are worn. This wear process generates particles that may become airborne and thus affect human health. The long term purpose of ‘Airborne particles in Rail transport’ project is to gain knowledge on the wear mechanisms in order to find means of controlling the number and size distribution of airborne particles. In this regard, a series of full-scale field tests and laboratory tests with a pin-on-disc machine have been conducted. The morphology and the matter of particles, along with their size distribution and concentration, have been studied. The validity of results from the pin-on-disc simulation has been verified by the field test results. Results show an ultra-fine peak for particles with a diameter size around 100 nm in diameter, a dominant fine peak for particles with a size of around 350 nm in diameter, and a coarse peak with a size of 3-7 μm in diameter. Materials such as iron, copper, aluminium, chromium, cobalt, antimony, and zinc have been detected in the nano-sized particles.

  • 5.
    Aiso, Toshiharu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Effect of combined additions of Si, Mn, Cr and Al to carbon steel on material transfer in a steel/TiN coated tool sliding contact2017Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 388-389, s. 9-17Artikel i tidskrift (Refereegranskat)
    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.

  • 6.
    Aiso, Toshiharu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Kubota, Manabu
    Nippon Steel & Sumitomo Metal Corporation.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Effect of Si and Al additions to carbon steel on material transfer and coating damage mechanism in turning with CVD coated tools2016Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 368-369, s. 379-389Artikel i tidskrift (Refereegranskat)
    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.

  • 7. Alemani, Mattia
    et al.
    Gialanella, S.
    Straffelini, G.
    Ciudin, R.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Perricone, G.
    Metinoz, I.
    Dry sliding of a low steel friction material against cast iron at different loads: Characterization of the friction layer and wear debris2017Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 376-377, s. 1450-1459Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pin-on-disc testing was used to investigate the sliding behavior and the wear products of a low-steel friction material against a cast iron disc at different applied loads, to investigate the effect of the temperature rise induced by frictional heating. The testing rig was operated in a clean chamber with a purified incoming air flux. The outgoing flux carries the wear particles to an impactor that counted and sorted them by average diameter and weight. At increasing applied loads, corresponding to a proportional increase of the pin-disc contact temperature, the coverage of both the pin and disc surface by a friction layer was found to increase too. The relevant X-Ray diffraction patterns revealed the presence of a large amount of graphite and different compounds originating from the friction material and from the counterface disc, mainly iron oxides, as concerns this latter. After the test at the lowest investigated load, i.e., 1 kg, the disc worn surface exhibited abrasive grooves and a discontinuous friction layer mainly made of compacted iron oxide particles. After the test at higher loads, i.e., 5 and 7 kg, the disc surface was covered by a compact friction layer. As concerns the friction layer on the pins, most of the ingredients from the friction material were detected, in association with the iron oxides from the disc. These results can be interpreted in terms of the temperature stability range of the phenolic resin used as a binder of the friction material. The characterization of the collected airborne wear debris showed that the particles produced by the low temperature (i.e., low load) test were mostly equiaxed; whereas those produced by the high temperature (i.e., high loads) tests, predominantly displayed a plate-like morphology. The mechanisms of their formation in relation to the characteristics of the friction layers are illustrated and discussed.

  • 8.
    Alemani, Mattia
    et al.
    KTH.
    Wahlström, Jens
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Tillämpad maskinteknik (KTH Södertälje). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    On the influence of car brake system parameters on particulate matter emissions2018Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 396, s. 67-74Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of car brake system parameters on particulate matter emissions was investigated using a pin-on-disc tribometer. Samples from a low-steel friction material and a cast iron disc were tested for different sliding velocities, nominal contact pressures and frictional powers. Disc temperatures were also measured. Their impact on total concentration, size distribution, particle coefficient and transition temperature was analysed. Results show that frictional power is the most significant brake system parameter. However, temperature, as a response parameter, is the most influential, inducing a shift towards the ultrafine particulate fraction and raising emissions. A transition temperature, independent of the system parameters, was identified.

  • 9.
    Alfredsson, Bo
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Dahlberg, Johan
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Olsson, Mårten
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    The role of a single surface asperity in rolling contact fatigue2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, nr 9-10, s. 757-762Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of contact loading of single surface irregularities, i.e. asperities, as an underlying mechanism for surface initiated rolling contact fatigue was investigated numerically using FEM. Spalls in the teeth flanks of driving gear wheels were investigated for typical spalling crack initiation properties. The spalling entry angle was documented and some spalls with a convex entry tip were found. The residual surface stresses of the used teeth, with spalls, were measured with the hole drilling technique. The gear contact close to the rolling circle was modelled as two rolling cylinders. A single asperity was introduced into the contact surface of one of them. Due to the presence of the asperity a three dimensional contact model was required. The material description included J(2)-plasticity with isotropic and linear hardening. The simulation included residual stresses from material heat treatment. The first roll cycle introduced plastic deformation which altered the residual stresses. Thus, the stress results were captured during a second roll cycle. The most important result was that asperities will serve as local stress raisers in the contact surfaces. The computed stress cycle at the asperity was compared to stress cycles that gave ring/cone cracks at point loaded experiments. The principal stress trajectory into the material was compared to the cross-section profiles of the spalling entry and ring/cone crack. The surface stress profile at the asperity was compared to the convex surface profiles of the spalling tip and ring/cone crack. The asperity deformation and change in residual surface stresses from moderate plastic deformation during rolling were estimated.

  • 10.
    AlMotasem, Ahmed Tamer
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). Assiut University, Egypt.
    Bergström, Jens
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Gåård, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Holleboom, Thijs
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Tool microstructure impact on the wear behavior of ferrite iron during nanoscratching: An atomic level simulation2017Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 370-371, s. 39-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, molecular dynamics simulations were used to investigate the impact of the tool microstructure on the wear behavior of ferrite workpiece during nanoscratching. The tool microstructure was modified by varying the carbide (cementite) contents. The simulation results show that dislocations are the primary mechanism for plastic deformation of the workpiece material. It is found that total dislocation length varies significantly depending on the carbide content in the tool. Furthermore, other tribological phenomena were also observed to depend on the carbide contents. For example, the average value of frictional forces decreased while the normal force increases with increasing carbide contents, and hence the friction coefficient was decreased. Additionally, the shape and size of lateral and frontal pileups are lowered. The structural analysis of the pileup region reveals the loss of long range order and start of amorphisation. The temperature distribution of the pileup regions showed an increase of the pileup temperature when carbide is added into tool. The wear volume is considerably reduced when the carbide content increases. The average scratch hardness was found to decrease and the result was analyzed with the theoretical Taylor hardening model.

  • 11.
    Alonso, Asier
    et al.
    CAF I D, Beasain, Spain.;Univ Navarra, TECNUN, Donostia San Sebastian, Spain..
    Casanueva, Carlos
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Perez, Javier
    CAF SA, Beasain, Spain..
    Stichel, Sebastian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Modelling of rough wheel-rail contact for physical damage calculations2019Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 436, artikel-id 202957Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work presents the initial steps given in order to obtain a comprehensive physical damage model for the specific case of wheel rail contact wear, which would be able to relate contact conditions, material properties and wear rates. The main advantage of a physical damage wear model is that wheelset and rail manufacturers can perform simulations in order to improve and optimise material properties for different operational cases. The work in this paper focuses on delaminative wear, starting with the importance and modelling of rough contact, and a comparison against classic smooth contact models.

  • 12.
    Andersson, Joel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Almqvist, Andreas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Numerical simulation of a wear experiment2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, nr 11-12, s. 2947-2952Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A wear model including a deterministic FFT-accelerated contact mechanical tool to calculate pressure and elastic-plastic deformation, is employed to simulate the time dependent wear in a sphere on flat contact. The results of the wear simulations compared to experimental results from a reciprocating test in a ball on disk tribometer. The conditions of the simulations and the experiments are independently adjusted to match up. Similarities and differences shows upon the usefulness and limitation of wearmodelling of this type.

  • 13. Andersson, P
    et al.
    Koskinen, J
    Varjus, S
    Gerbig, Y
    Haefke, H
    Georgiou, S
    Zhmud, B
    YKI – Ytkemiska institutet.
    Microlubrication effect by laser-textured steel surfaces2007Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 262, s. 369-379Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The beneficial effect on lubrication achieved through microtexturing by laser ablation was investigated. The investigation was based on two independent experimental approaches with oil-lubricated smooth and laser-textured steel surfaces in oscillating sliding contact with a steel ball. Two types of laser-textured patterns of microcavities were studied. It was found that, in comparison with smooth steel surfaces, the laser texturing significantly reduces friction and wear. The most significant improvement in the tribological performance was achieved with an oil of high viscosity combined with a texture comprising a low density of deep microcavities.

  • 14.
    Andersson, Sören
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Söderberg, Anders
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    A random wear model for the interaction between a rough and a smooth surface2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, nr 9-10, s. 763-769Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contact surfaces in many applications change form due to plastic and elastic deformation and to wear. This study focused on the plastic deformation and wear of the asperities on a rough surface rubbing against an opposite smooth, hard and wear-resistant surface. A stochastic model for the prediction of plastic deformations and wear of a rough surface is proposed. The surface roughness and the interaction between the surfaces are also represented by stochastic models. A single asperity is studied as it comes into contact and interacts with the opposite surface. Since the wear process is simulated as an initial-value problem, the proposed general wear model is formulated as a first order differential equation system representing events during the rubbing process at all of the asperities considered on a surface.

  • 15.
    André, Benny
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Friction and contact resistance of nanocomposite Ti-Ni-C coatings2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, nr 9-10, s. 555-566Artikel i tidskrift (Refereegranskat)
    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.

  • 16.
    Angserud, Jenny
    et al.
    Sandvik Mining.
    From, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wallin, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Norgren, Susanne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    On a wear test for rock drill inserts2013Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 301, nr 1-2, s. 109-115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work wear of cemented carbide rock drill inserts is evaluated by using a rotating rock cylinder as counter surface. The influence on wear rate and degradation mechanisms from varying dry and wet conditions, cemented carbide grade, abrasive particle type and size as well as load is studied. The used abrasive media are alumina and silica.

    Test results show high repeatability and the three tested cemented carbide grades can be differentiated, even though their relative difference in sample hardness is modest. The loads used, 100–200 N, are sufficiently high to cause fracture and wear of the granite rock. The degraded microstructure of inserts tested under wet and dry conditions as well as with added silica particles is similar to field worn inserts. Hence, the same wear mechanisms occur and the test successfully mimics rock drill wear. Typical insert wear includes cracking and fragmentation of WC grains, depletion of Co binder phase and adhered material originating from the rock.

    Tests under dry conditions always cause less measured wear than tests under wet conditions.

    Addition of alumina particles, which are harder than the used cemented carbide samples, causes a significant wear rate increase but does not provide wear similar to rock drilling.

  • 17. Anmark, Niclas
    et al.
    Bjork, Thomas
    Ganea, Anna
    Olund, Patrik
    Hogmark, Sture
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Karasev, Andrey
    Jonsson, Par Goran
    The effect of inclusion composition on tool wear in hard part turning using PCBN cutting tools2015Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 334, s. 13-22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work reports on hard part turning of carburizing steels using a PCBN cutting tool in fine machining. Emphasis is on the link between composition of the inclusions in work material and wear mechanisms of the cutting tool. A Ca-treated machinability improved 20NiCrMo steel was included together with three other carburizing steels with different inclusion characteristics. Machining tests were conducted to examine cutting tool life and its balance between excessive flank wear and crater wear. The wear mechanisms were examined using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS) and a secondary electron (SE) detector. The longest tool life was obtained when cutting the Ca-treated steel. The improved machinability is linked to the deposition of complex (Mn,Ca)S and (Ca,Al)(O,S) protective slag layers that form on the rake face of the cutting tool during machining. Cutting in this steel also resulted in a typical ridge formation in the tool edge crater. Transfer of workpiece material to the rake face crater is characteristic in hard part turning of steel with high cleanliness. This is suggested to be related to the lack of the sulfides that lubricate conventional machinability treated steels, and that the crater wear of low-sulfur steel is more pronounced than for steels with higher sulfur content.

  • 18.
    Bakoglidis, Konstantinos
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Glenat, Herve
    Technosud, France.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schmidt, Susann
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Grillo, Stefano
    Technosud, France; University of Perpignan, France.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Comparative study of macro- and microtribological properties of carbon nitride thin films deposited by HiPIMS2017Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 370Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The macro- and microtribological properties of carbon nitride thin films deposited by high power impulse magnetron sputtering at different substrate bias voltages (V-b) were investigated. V-b of -100, -150, -200, and-300 V were used. A Hysitron Triboindenter TI950 and a reciprocating Tribotechnic tribometer with diamond counterparts were used in order to assess the tribological performance of the films at the micro- and macroscale, respectively. Initial Hertzian contact pressures of 2.5 GPa, 3.3 GPa and 3.9 GPa were chosen for the comparative measurements at both scales. At the macroscale, films with higher initial roughness present an increased wear. Debris creation and asperity deformation takes place causing abrasive wear. At the microscale, compression of the surface material occurs. The run-in friction shows similar trends at both scales; an initial decrease and an increase thereafter. Steady-state friction is not reached at the microscale, attributed to the absence of a graphitic tribolayer in the contact. At the macroscale, all films show abrasive wear and debris creation. Here, the changes in friction coefficients are attributed to the debris loss from the contact during the tribotests. The CN film tested at 2.5 GPa shows a continuous increase of friction, due to the continuous loss of debris from the contact. The other films reach a steady-state friction coefficient, since most of the debris is lost before the end of the tribotests. (C) 2016 Elsevier B.V. All rights reserved.

  • 19.
    Bakshi, S. Das
    et al.
    Materials Science and Metallurgy, University of Cambridge.
    Leiro, Alejandro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Prakash, Braham
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Bhadeshia, H.K.D.H.
    Materials Science and Metallurgy, University of Cambridge.
    Dry rolling/sliding wear of nanostructured bainite2014Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 316, nr 1-2, s. 70-78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The abrasive wear of carbide-free bainitic steel under dry rolling/sliding conditions has been studied. It is demonstrated that this nanostructure, generated by isothermal transformation at 200 °C, has a resistance to wear that supersedes that of other carbide-free bainitic steels transformed at higher temperatures. The experimental results, in combination with a theoretical analysis of rolling/sliding indicates that under the conditions studied, the role of sliding is minimal, so that the maximum shear stresses during contact are generated below the contact surface. Thus, the hardness following testing is found to reach a maximum below the contact surface. The fine scale and associated strength of the structure combats wear during the running-in period, but the volume fraction, stability and morphology of retained austenite plays a significant role during wear, by work-hardening the surface through phase transformation into very hard martensite

  • 20.
    Berggren, Eric
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    A new approach to the analysis and presentation of vertical track geometry quality and rail roughness2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 265, s. 1400-1496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new approach on enhancing the assessment of track geometry quality and rail roughness by means of train–track interaction simulation and wavelength content analysis is presented. The dynamic model includes vehicle, track and linearized wheel–rail contact with moving irregularities and can be simulated either in the frequency domain by using FFT or in the time domain by constructing a filter function based on system identification technique. The system is suitable to calculate wheel–rail forces for very long track sections and for several vehicle types under a wide range of travelling speeds since the computational scheme is very efficient (300 km/s on a standard computer). With numerical results we demonstrate the potential benefits of improving conventional track geometry inspection methods and highlight short defects (0.5–2 m) as a cause of high dynamic wheel–rail interaction forces. By using a wavelength weighting of measured rail roughness a new improved way of analyzing rail roughness data is also presented. This improves condition assessment of tracks and rails and will enable the track engineer to monitor the track in a better way.

  • 21.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Henriksson, Mats
    Scania CV .
    Dizdar, Senad
    Höganäs AB.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Effects of thrust washer bearing surface characteristics on planetary gear train wear2019Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 432-433, artikel-id 202933Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thrust washers in spur planetary gears are placed between the planet wheel and planet carrier and act as spacers and wear pads. Metal to metal sliding contact between the planet wheel – washer – carrier causes frictional power losses that, combined with starved lubrication, may cause high contact temperatures and thermo-mechanical effects that potentially trigger thermo-elastic instabilities and excessive local wear. The planetary gear system would benefit from a low-friction interface between the washer and the planet wheel. Five washers with different surface treatments were tested in a full-scale gear rig. These tests were also replicated as closely as possible in a pin-on-disc tribometer. The following types of finishing material treatments were studied: a chemical nickel coating plus polymer on a nitro-carburised surface, a combination of nitro-carburization and solid lubricant layers, electroless deposited chemical nickel coating plus polymer, nitro-carburizing, and manganese phosphating. The frictional results indicate that tribometer tests can be used to compare and classify new washer materials. Lab scale tests show that a new experimental self-lubricating tribomaterial that was applied with laser cladding has a promising potential to increase planetary gear train robustness and service life, especially if the surface is fine grinded.

  • 22. Beste, Ulrik
    et al.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    A new view of the deterioration and wear of WC/Co cemented carbide rock drill buttons2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, nr 11-12, s. 1129-1141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    WC/Co cemented carbide is a material developed for highly demanding applications. The unique combination of hardness and toughness makes it especially suitable for wear resistant parts of tools for rock drilling. The wear of cemented carbide rock drill buttons has been the focus of numerous studies, and a large amount of wear data has been published. However, the broad range of possible wear mechanisms, the large number of rock types of very different character, and finally the large local property variations even within a single drill hole, has made it difficult to sort out a good general understanding. One conclusion stands out very clear: the wear data for one rock drill in one rock type is unique to that particular situation and should not be expected to apply to other rock drills in other rock types. Even so, some general wear mechanisms can be observed. Against this backdrop, this paper seeks to present a new, more comprehensive, view on the deterioration and wear mechanisms of cemented carbide rock drill buttons. The new view combines some of most important aspects, including two life limiting factors, five classes of mechanisms of deterioration and five classes of material removal mechanisms. The view is based on careful high resolution investigations of worn rock drill buttons selected from drilling of different rock types. The deterioration includes a fundamental change of material and properties due to intermixing of rock material and cemented carbide in the surface layer of the button. It further includes corrosive decay and oxidation of WC and formation of large-scale cracks in a reptile skin pattern.

  • 23. Beste, Ulrik
    et al.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Targeting micro-sectioning: A technique to study subsurface features in worn specimens2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, nr 11-12, s. 1152-1156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Traditional preparation of metallographic cross sections by cutting, polishing and etching has a long and successful history of revealing grain sizes, phase composition, gradients, etc. However, the technique is limited with respect to precision in the positioning of the cross section, and it also tends to inadvertently remove brittle constituents and conceal cracks and small details close to ductile phases, that may become smeared out by the polishing. The present paper presents an alternative cross sectioning technique for worn surfaces, developed to automatically reveal weak zones in the surface layer of a material, without the need of precise positioning, and also avoiding inadvertent removal of brittle phases. The technique is applicable to materials that exhibit brittle fracture, and is normally used for characterisation of unworn materials. It is primarily intended for studies in the SEM, since the cross sections produced typically exhibit too coarse topography to be sharply pictured in the light optical microscope. The simple and rapid preparation technique is described and examples from worn cemented carbide rock drills and hot rolls are presented to illustrate some of the capabilities of the technique.

  • 24. Beste, Ulrik
    et al.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Hogmark, Sture
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Rock penetration into cemented carbide drill buttons during rock drilling2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, nr 11-12, s. 1142-1151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In percussive and rotary percussive rock drilling, the rock is crushed into small fragments by the repeated hard impact of the drill bit, and subsequently removed by flushing water or air. To avoid excessive wear, the steel drill bit is equipped with a set of cemented carbide buttons that protrude from the bit to take the actual impact. The severe contact against the rock results in some wear of the button, but also in formation of surface layers of rock material and penetration and impregnation of rock material into the cemented carbide structure. This situation, with serious implications for the wear and fracture of the buttons, have previously not been reported. The present findings represent a significantly new understanding of the wear of the rock button material. The deterioration mechanisms are described in detail, using examples from a range of real drilling applications in different rock types. During operation, material in the surface layer of the drill button shifts from that of the original cemented carbide into an uncontrolled composite. This composite is formed by the WC carbide hard phase and a binder consisting of a mixture of cobalt and rock. This new material should be expected to exhibit properties significantly different from the original cemented carbide.

  • 25.
    Bolelli, G.
    et al.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria 'Enzo Ferrari', Via P. Vivarelli 10/1, Modena, MO, Italy .
    Berger, L.-M.
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, Dresden, Germany.
    Börner, T.
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, Dresden, Germany.
    Koivuluoto, H.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, Tampere, Finland .
    Matikainen, V.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, Tampere, Finland .
    Lusvarghi, L.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria 'Enzo Ferrari', Via P. Vivarelli 10/1, Modena, MO, Italy .
    Lyphout, Christophe
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Sassatelli, P.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria 'Enzo Ferrari', Via P. Vivarelli 10/1, Modena, MO, Italy .
    Trache, R.
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, Dresden, Germany .
    Vuoristo, P.c
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, Tampere, Finlan.
    Sliding and abrasive wear behaviour of HVOF- and HVAF-sprayed Cr3C2-NiCr hardmetal coatings2016Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 358-359, s. 32-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper provides a comprehensive characterisation of HVOF- and HVAF-sprayed Cr3C2–25 wt.% NiCr hardmetal coatings. One commercial powder composition with two different particle size distributions was processed using five HVOF and HVAF thermal spray systems.All coatings contain less Cr3C2 than the feedstock powder, possibly due to the rebound of some Cr3C2-rich particles during high-velocity impact onto the substrate.Dry sand-rubber wheel abrasive wear testing causes both grooving and pull-out of splat fragments. Mass losses depend on inter- and intra-lamellar cohesion, being higher (≥70 mg after a wear distance of 5904 m) for the coatings deposited with the coarser feedstock powder or with one type of HVAF torch.Sliding wear at room temperature against alumina involves shallower abrasive grooving, small-scale delamination and carbide pull-outs, and it is controlled by intra-lamellar cohesion. The coatings obtained from the fine feedstock powder exhibit the lowest wear rates (≈5x10−6 mm3/(Nm)). At 400 °C, abrasive grooving dominates the sliding wear behaviour; wear rates increase by one order of magnitude but friction coefficients decrease from ≈0.7 to ≈0.5. The thermal expansion coefficient of the coatings (11.08x10−6 °C−1 in the 30–400 °C range) is sufficiently close to that of the steel substrate (14.23x10−6 °C−1) to avoid macro-cracking

  • 26.
    Braceras, Inigo
    et al.
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Ibanez, Inigo
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Taher, Mamoun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Mao, Fang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    del Barrio, Andres
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Saenz De Urturi, Saioa
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Berastegui, Pedro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Andersson, Anna M.
    ABB AB, Corp Res, Insulat & Mat Technol, SE-72178 Vasteras, Sweden.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    On the electro-tribological properties and degradation resistance of silver-aluminum coatings2018Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 414, s. 202-211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contact materials in sliding electrical applications must possess low electrical contact resistance, low friction and wear coefficients, and high degradation resistance to the surrounding media. Silver coatings are commonly used in such applications despite their shortcomings. This work has focused on the study of alternative silver-aluminum coatings deposited by PVD. The main findings include the strong dependence of the tribological performance on the concentration of Al and hence the phases present in the coatings. Besides, the wear mechanism was found to be affected by the working media, either on air or insulating oil. Results have shown that for full HCP phase coatings (Ag67Al33), wear rates are lowest, with no adhesive wear and good surface sulphidation resistance, though with some proclivity to oxidation, coupled with a moderate increase in the electrical contact resistance.

  • 27.
    Brewe, David E.
    et al.
    Lewis Research Center.
    Jacobson, Bo
    Luleå tekniska universitet.
    The effect of vibration amplitude on vapour cavitation in journal bearings1987Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 115, nr 1-2, s. 63-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Computational movies were used to analyse the formation and collapse of vapour cavitation bubbles in a submerged journal bearing. The effect of vibration amplitude on vapour cavitation was studied for a journal undergoing circular whirl. The boundary conditions were implemented using Elrod's algorithm which conserves mass flow through the cavitation bubble as well as the oil film region of the bearing. In the calculations, 0.1 ε εmax, where ε is the instantaneous eccentricity and 0.4 εmax 0.9 for the different cases studied. For the case 0.1 ε 0.4, no vapour cavitation occurred. For the case in which 0.1 ε < 0.9, vapour cavitation was present for 76% of the total time

  • 28. Broitman, E.
    et al.
    Hellgren, N.
    Wanstrand, O.
    Wänstrand, O., Department of Materials Science, Ångström Laboratory, Uppsala University, SE-751 21 Uppsala, Sweden.
    Johansson, M.P.
    Berlind, Torun
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Sjostrom, H.
    Sjöström, H., Sjöstrom Coating Consulting, KarlGustavsgatan 21A, SE-411 20 Göteborg, Sweden.
    Sundgren, J.-E.
    Office of the President, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Larsson, M.
    Department of Materials Science, Ångström Laboratory, Uppsala University, SE-751 21 Uppsala, Sweden.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Mechanical and tribological properties of CNx films deposited by reactive magnetron sputtering2001Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 248, nr 1-2, s. 55-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hardness, elasticity, wear rate and friction coefficient of carbon nitride (CNx) films of defined microstructure and composition are presented. CNx films were deposited by dc reactive magnetron sputtering from a C target in N2/Ar plasma. Films were grown on Si (001), Ni, and HSS substrates to thickness of ~0.5 µm at a total pressure of 3 mTorr with the N2 fraction varied from 0 to 1, and the substrate temperature Ts, varied from ambient to 350°C. The mechanical and tribological properties of the coatings were evaluated by nanoindentation and dry ball-on-disk test. For CNx (0 = x = 0.35) films deposited below 200°C (amorphous structure), the elastic recovery and hardness do not change significantly with increasing N concentration, however, the friction coefficient increases from 0.19 to 0.45, while the coating wear rate is low. For CNx (0 = x = 0.15) films grown at Ts = 350°C, where a transition from a graphite-like to a "fullerene-like" phase occurs, a dramatic increase in hardness and elasticity is observed. Furthermore, the rms surface roughness decreases from 15.0 to 0.4 nm. For 0.15 = x = 0.20, CNx films deposited at Ts = 350°C (fullerene-like phase) exhibit a smooth surface, high hardness and elasticity (~90% recovery), and a coefficient of friction against hard steel of ~0.25. For all substrates, film friction coefficient tends to increase as the nitrogen content in the film is increased. Results also indicate the formation of a transfer layer which improves the tribological properties of the films. © 2001 Elsevier Science B.V. All rights reserved.

  • 29.
    Cabanettes, Frederic
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS). Halmstad Univ, Sch Business & Engn, SE-30118 Halmstad, Sweden..
    Rosén, Bengt Göran
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Topography changes observation during running-in of rolling contacts2014Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 315, nr 1-2, s. 78-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The automotive industry and the design of engines are strongly ruled by performance and legislation demands. In the valve train, besides the main function (transformation of rotation to translation movements) to fulfill, new requirements in environmental demands and performance in terms of wear are leading to more and more detailed studies of the cams and rollers. Wear reduction studies for prolonging lifetime of these components require decreasing the scale of observation down to roughness. Among the different wear stages of a component, the running-in is a crucial period which will greatly influence the lifetime and performance of components. The aim of this paper is to analyze the topography variations observed during the running-in of a camshaft on a valve train rig test. A truck engine's camshaft is run under realistic conditions and 3D surfaces are measured before and after the test by using relocation techniques. By measuring the very same surfaces before and after the experiment, a deep analysis of the running-in effects on surfaces can be performed. 3D surface roughness parameters are used in parallel with new proposed methods of analysis. As a result, the mechanisms involved during running-in are emphasized and can be used for further simulations and optimization of the cam roller contact. (C) 2014 Elsevier B.V. All rights reserved.

  • 30.
    Cabanettes, Frédéric
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Claret-Tournier, Julien
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK).
    Mohlin, Johan
    Finnveden Powertrain.
    Nilsson, P.-H.
    Volvo Technology Corporation.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Xiao, L.
    Volvo Powertrain Corporation.
    The evolution of surface topography of injection cams2009Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, nr 5-6, s. 570-573Artikel i tidskrift (Refereegranskat)
  • 31.
    Carlsson, Per
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Bexell, Ulf
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Friction and Wear Mechanisms of Thin Organic Permanent Coatings Deposited on Hot-Dip Coated Steel2001Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 247, nr 1, s. 88-99Artikel i tidskrift (Refereegranskat)
    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.

  • 32. Casas, B.
    et al.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lanes, L.M.
    Hogmark, Sture
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Adhesion and abrasive wear resistance of TiN deposited on electrical discharge machined WC-Co cements rbides2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 265, nr 3-4, s. 490-496Artikel i tidskrift (Refereegranskat)
    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.

  • 33.
    Courbon, Cedric
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Fallqvust, M.
    R&D Materials and Technology Development, Seco Tools AB, Fagersta.
    Hardell, Jens
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    M'Saoubi, R.
    R&D Materials and Technology Development, Seco Tools AB, Fagersta.
    Prakash, Braham
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Adhesion tendency of PVD TiAlN coatings at elevated temperatures during reciprocating sliding against carbon steel2015Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 330-331, s. 209-222Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work focussed on assessing the contact conditions driving the adhesion tendency of PVD TiAlN coated cemented carbide during reciprocating sliding against a normalized AISI 4137 carbon steel. A special emphasis is given to the surface topography of the coating. Results are analysed in terms of friction and material transfer over a large range of temperatures (up to 800 °C) and contact pressures. The post-test surface analysis of the specimens is conducted in order to understand the tribological behaviour and elucidate the formation mechanisms of transfer layers. A numerical model is developed to assess the amount of heat effectively transmitted into the first bodies and the temperature of the surfaces in contact.Whereas temperatures close to 400 °C ensure the formation of a stable tribofilm reducing friction, the highest temperatures lead to unstable frictional behaviour. Coating surface topography has been seen to be a major parameter driving material transfer during the first stages of the contact and the formation of a transfer layer. Thin and homogeneous layers are almost instantaneously formed with a polished surface whereas some time is required with a rougher one to form a film. A large amount of the frictional power is dissipated into these layers and high temperatures can be reached at the surface due to frictional heating. Contact pressure is found to be a parameter promoting transfer and oxidation

  • 34.
    Dahlberg, Johan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Alfredsson, Bo
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Transient rolling of cylindrical contacts with constant and linearly increasing applied slip2009Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, nr 1-2, s. 316-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The transient start problem of a rolling cylindrical contact has been studied. The transient conditions were controlled by the applied relative slip. Two cases with start of rolling from stationary contact were investigated, with constant and with linearly increasing applied slip. At each instant during the transition stage, it was assumed that the traction distribution could be approximated with the Carter traction for steady-state tractive rolling. Based on this distribution, approximate expressions were derived for the transient rolling distance and transient behaviour of the tangential load. The transient period could end in gross sliding or steady-state creep with the Carter traction distribution and stick-slip regions in the contact. The expressions and the transient traction distributions were validated numerically using FEM. Simulations with constant applied slip showed that when rolling started from a tangentially unloaded and unstrained position, the steady-state traction distribution by Carter was a good approximation of the actual transient traction distribution. The solution was accurate for transient rolling lengths longer than a quarter of the contact width. The transient behaviour depended on the bulk geometry of the structures. For the relatively stiff structure with two elastic steel cylinders, small amounts of relative slip and high coefficients of friction, the transient rolling distance, L-0, could become large. In the present study, examples with L-0 approximate to 40 . a were identified. Thus, situations exist for which the transient conditions might be important. The transient distance increased with smaller slip, larger coefficient of friction, lower bulk stiffness, higher contact normal loads and for more compliant materials. The spur gear contact interaction with varying slip was considered as a case study.

  • 35.
    Dimkovski, Zlate
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Anderberg, Cecilia
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Ohlsson, Robert
    Volvo Powertrain Corp., Volvo Group, Göteborg, Sweden.
    Rosén, Bengt - Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Characterisation of worn cylinder liner surfaces by segmentation of honing and wear scratches2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, s. 548-552Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The presence of the honing scratches/grooves in cylinder liner surfaces is intended and desired as they improve the lubrication and retain the debris reducing the piston assembly/liner friction and consequently improve the fuel economy and longevity of the internal combustion (IC) engines. Axial scratches caused by the abrasive wear between the tribological partners and/or entrained wear particles are undesired since they are correlated with increased oil consumption and noxious emissions of the IC engines. Due to the imperfection of the manufacturing process, the honing grooves, especially the deep ones, are smeared and interrupted by folds. A portion of the folds would eventually detach during the running process and act as abrasive particles increasing the wear in the cylinder. To closely examine the influence of all these features on the liner's function, it emerges a need to objectively quantify the axial wear scratches, plateau honing grooves, deep honing grooves and their interrupts. The existing techniques fail to segment a groove containing interrupts as they usually appear as summits at several locations in the course of the groove. Combining the profile and image analyses, the deep grooves and their interrupts were successfully identified and quantified in earlier works of the authors. In this paper those algorithms are extended, so that the deep honing grooves, plateau honing grooves and axial scratches crossing different depth levels are sequentially segmented in three levels/steps in an immersing way. A number of parameters derived from this method were utilised to compare 3D interference measurements from the top dead centre, middle and bottom region of a liner run in a truck engine test whereas the three regions represent different wear regimes due to the different running conditions. The results show that: (i) the axial scratches are densest in the top dead centre and about the same size as the plateau grooves in all three regions, while in the bottom region there are only few scratches; (ii) the presence of plateau grooves in the top region clearly decreases, (iii) the deep groove interrupt and coverage are lowest in the top region, and (iv) the groove height and distance between grooves spread mostly.

  • 36.
    Dimkovski, Zlate
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Anderberg, Cecilia
    Volvo Car Corporation, Göteborg, Sweden.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Ohlsson, Robert
    Volvo Power Train Corp., Volvo Group, Göteborg, Sweden.
    Thomas, Tom
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Quantification of the cold worked material inside the deep honing grooves on cylinder liner surfaces and its effect on wear2009Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, nr 12, s. 2235-2242Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increased presence of cold work material on cylinder liners due to the introduction of the diamond honing is undesirable as it seals the oil-bearing honing grooves. The most of it is a smeared metal inside the deep honing grooves (blechmantel) that may break and act as abrasive wear particles increasing the bore wear. An attempt has been made to estimate the extent of removal of blechmantel for different wear regimes present at the middle and top region (near the top dead centre) of the liner surface using the least worn bottom region as a reference for comparison. A number of truck grey iron cylinder liners were axially sectioned after varying periods of engine running under similar conditions of load, engine speed and lubrication. 3D surface measurements were taken at the three regions and a range of standard parameters was extracted. Combining the profile and image analysis, an algorithm was developed to identify and quantify the blechmantel. The algorithm has successfully identified/quantified the blechmantel and can be used for automatic surface quality and process control. It was found that the amount of the blechmantel in the middle section was approximately the same (though slightly lower) as that in the bottom section, while there was a considerable dislocation and removal of blechmantel in the top section and thereby it represents one of the possible causes for wear. Axial wear scratches of different size and distribution were observed not only through the whole stroke area, but also in the bottom region. All engines and liners performed well throughout the tests, and the observed quantities of blechmantel and axial scratches are acceptable for the time being.

  • 37.
    Dimkovski, Zlate
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Bååth, Lars
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Fotonik och mikrovågsteknik. Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Rosén, Stefan
    Toponova AB.
    Ohlsson, Robert
    Volvo Powertrain.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Interference Measurements of Deposits on Cylinder Liner Surfaces2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, nr 3-4, s. 247-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The accumulation of deposits in the honing grooves of the cylinder liner surfaces of internal combustion engines is undesirable as they seal the grooves (reducing their oil retention capability) and increase engine's oil consumption. As part of a long-term programme of truck engine development, after different running times and under similar conditions of load, engine speed and lubrication, a number of grey iron cylinder liners were axially sectioned, measured, inspected and a presence of deposits was discovered. These deposits were characterised in order to gain knowledge about their origin and quantities. The X-ray energy dispersive analysis revealed elements stemming from the oil/fuel (C, O and S), from the detergent (Ca and Mg), from the anti-wear additive (Zn and P), and from some contaminants (K and Si). Higher concentration of S and Ca were mostly found in the honing grooves covered with deposits suggesting a domination of the detergent additive. Deposit thickness measurements obtained by a white light interferometer revealed patchy deposit topographies concentrated at the top region reducing towards the bottom of the liner which was also confirmed by scanning electron microscope measurements. Despite the limitations of the interferometer, it has been shown that the interference measurements are sufficiently reliable for a quick and objective quantification of the overall deposit accumulation.

  • 38.
    Dirks, Babette
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Enblom, Roger
    Bombardier Transportation, Passengers Division - Specialist Engineering, Västerås, Sweden.
    Prediction model for wheel profile wear and rolling contact fatigue2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, nr 1-2, s. 210-217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A lifetime prediction tool for railway wheels and rails should be able to predict both wear and rolling contact fatigue (RCF), which are the two main deterioration phenomena. Several models exist to predict wear or RCF, but not many models exist which can predict both. In this study, two of these RCF prediction models have been extended. The performance of these models has been studied through a parametric study where multi-body simulations (MBS) provided the input to the models. The influences of several parameters which can have an effect on the wheel/rail life have been studied in order to find the behaviour of the different models. These parameters are: curve radius, worn wheel and rail profiles, coefficient of friction, primary stiffness, track irregularities, and cant deficiency. This paper describes the differences between the two models and shows that the adjustments of the models have a significant influence on RCF prediction.

  • 39.
    Dirks, Babette
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Enblom, Roger
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. Bombardier Transportation, Sweden .
    Berg, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Prediction of wheel profile wear and crack growth - comparisons with measurements2016Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 366, s. 84-94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A model which can predict the length of the surface crack and crack depth in rails was developed in a previous study by the authors B. Dirks, R. Enblom, A. Ekberg, M. Berg (2015) []. In the present study, verification of this crack prediction model in combination with a wear prediction model was done against wheel measurements. For a period of 15 months, the wheels of three units of a Stockholm commuter train were measured with respect to wear and crack development for verification of the wheel life prediction tool. Vehicle-track dynamics simulations were used to calculate the forces and contact positions for the wear and crack prediction models. It can be concluded that the wear prediction model gives reasonable results, especially considering the large scatter in the wheel profile measurements. Although the wheel life prediction tool could not be verified, since the crack prediction model had to be recalibrated for the current wheel application, the results appear promising.

  • 40.
    Elo, Robin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Heinrichs, Jannica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wear protective capacity of tribofilms formed on combustion engine valves with different surface textures2017Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 376-377, s. 1429-1436Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The valve system controls the flow of gases into and out of the cylinders of combustion engines. As the combustion chamber is repeatedly filled with air and emptied from combustion residues, the contacting surfaces of the valve and valve seat insert (VSI) are exposed to high temperatures, high speed impacts, corrosive environment and high closing forces. Since the expected wear life of the components is hundreds of millions of operational cycles, the wear rate has to be extremely low. Previous studies have shown that this is accomplished by the continual formation of protective tribofilms on the surfaces, formed from oil additive residues. For some stationary gas engines, seemingly random occurrence of severe wear, i.e. without correlation to special running conditions, calls for an improved understanding of the wear protective abilities of these tribofilms. Further, the potential of making the protection more robust by using simple textures on sealing surfaces is investigated. Real valves and VSI's were therefore run in a dedicated test rig, previously shown capable of forming tribofilms similar to those found in real engine valves. Two surface textures, turned or ground, were tested. After a running in phase where fully covering tribofilms were formed, the tests were continued without adding the oil residues needed for replenishing the tribofilm. The flow of oil residues was either completely stopped or only intermittently open. The resulting wear was monitored during testing and after finishing the tests remaining tribofilms were analysed with SEM and EDS. The severity of the wear was graded and the presence of tribofilm and localization of wear was correlated. The endurance of the tribofilms was surprisingly high for both textures. Typically the tribofilms exhibited better wear resistance than the underlying metals. Once fully formed, the tribofilms can therefore endure for a long time without addition of new tribofilm forming material. Both textures showed the first sign of wear after roughly the same time and then followed the same progression, when the flow of oil residues was cut. With the intermittent oil residue supply, both textures performed even better. Especially the turned texture showed only slow, mild wear.

  • 41.
    Elo, Robin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Jacobson, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Formation and breakdown of oil residue tribofilms protecting the valves of diesel engines2015Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 330-331, s. 193-198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The contacting surfaces of modern valve systems experience a complex contact situation with repeated micro sliding at high temperatures and pressures. The wear rate of the surfaces has to be extremely low to fulfill the high demands on engine efficiency during its entire life-time-wear will cause valve recession and thus make the combustion less efficient. In addition to this, legislation requires reduced particulates in the emissions, which leads to aggravating conditions for the valves. Studies of field samples from well-functioning engines have shown that a protective tribofilm is formed on the contacting surfaces of the valve. This tribofilm is primarily built up from combustion residues of the engine oil and fuel, making its composition sensitive to their additives. Since the low wear rate is dependent on the formation of a tribofilm based on oil residues, while future legislation will demand even cleaner emissions, a deepened understanding about the formation and dynamics of these tribofilms is needed. How quickly are they formed, how quickly do they wear, do they require constant supply of "building material", can they efficiently protect the surfaces also when substantially less building material is available? In the present study, the formation and breakdown mechanisms of this type of protective tribofilms have been investigated in a specifically designed valve rig. This rig uses real engine components and allows controlled addition of oil mist (in the present case from a fully formulated engine oil) into a hot air stream, passing the operating valve. Four phases were identified in the tribofilm dynamics. In the first-formation-phase, oil residue particles become trapped on the sealing surfaces of the valve, and then smeared out between the closing surfaces to form a covering tribofilm. In the second-equilibrium-phase, the tribofilm coverage is stable, meaning that the addition of new particles is balanced by wear of the film. Two types of films form, one thick carbon-based film and one thinner additive-based film. If the supply of oil is cut off, the third-breakdown-phase commences. Here the carbon-based film is quickly removed while the additive-based film keeps protecting the valve surface for numerous closing cycles. When also this film become worn through, the final phase-wear of exposed valve material -commences, involving severe wear and oxidization. Interestingly, it was found that the breakdown was slower if the equilibrium phase was longer, indicating that the additive-based tribofilm becomes more durable by being more worked.

  • 42.
    Emmerlich, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Gassner, Gert
    Department of Physical Metallurgy and Materials Testing, University of Leoben, Austria.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Micro and macroscale tribological behavior of epitaxial Ti3SiC2 thin films2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, nr 11-12, s. 914-919Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti3SiC2(0 0 0 1) thin films prepared by magnetron sputtering were investigated for their response to tribomechanical strain induced during ball-on-disk experiments with 6 mm alumina balls and scratch tests with a 1 μm cono-spherical diamond tip. Normal loads of 100 μN to 0.24 N were applied resulting in a friction coefficient of 0.1 for the low loads. With higher applied normal loads, the friction coefficient increased up to 0.8. Analysis of the wear tracks using atomic force microscopy, scanning electron microscopy, and Raman spectroscopy revealed excessive debris resulting in third-body abrasion and fast wear. The formation of the debris can be explained by the generation of subsurface delamination cracks on basal planes. Subsequent kink formation obstructs the ball movement which results in the removal of the kinked film parts.

  • 43.
    Enblom, Roger
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
    Berg, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Impact of non-elliptic contact modelling in wheel wear simulation2008Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 265, nr 9-10, s. 1532-1541Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Advances in simulation of railway wheel wear in the sense of material removal have drawn the attention to the importance of wheel–rail contact modelling. As a further step of enhancing the used simulation procedure in direction of increased generality and reduced need for application-dependent calibration, the focus of this investigation is the influence of non-elliptic contact models on the wheel wear rate and profile shape. To facilitate evaluation the semi-Hertzian contact procedure Stripes, developed by INRETS in France, has been implemented.

    To investigate the capabilities of Stripes to assess the contact area and pressure, shape comparisons have been made with other numerical methods for a set of wheel–rail contact situations. The referenced results are based on the linear elastic half-space assumption, elastic finite element analysis, and elastic–plastic finite element analysis. For reference also the elliptic contact area according to Hertz is shown as given by the contact data table of the multi-body simulation code.

    After exploring the properties of the Stripes procedure with respect to contact area estimation and pressure distribution, the focus is moved to the influence on wear rate, being the principal objective of this investigation. First the wear distribution over the contact patch is studied and compared to results using the elliptic model from the MBS code Gensys and the non-elliptic approach with Kalker's code Contact. Finally the evolution of the wheel profile is simulated for a few typical cases.

    This investigation of wear distributions over non-elliptic patches under different operating conditions indicates significant differences compared to both Contact and the applied Hertzian approach. The expansion from single contact occasions to complete simulations indicates comparable material removal rates but relocation towards the flange side. This tendency is apparent in all of the cases shown, however limited to initial wear in tangent run or reasonably mild curve negotiation.

  • 44.
    Enblom, Roger
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Berg, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Simulation of railway wheel profile development due to wear: influence of disc braking and contact environment2005Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 258, nr 7-8, s. 1055-1063Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper addresses issues related to braking and wheel-rail contact conditions in the context of wheel wear simulation. The KTH approach to the topic includes Archard's wear model with associated wear maps, vehicle dynamics simulation and railway network definition. In previous work at KTH certain variations in operating conditions have been accounted for through empirically estimated average scaling factors. The objective of the current research is to be able to include such variations in the set of simulations. In particular the influence of disc braking as well as varying friction and lubrication conditions are investigated. Both environmental factors like moist and contamination and deliberate lubrication need to be considered. As part of the associated contact analysis the influence of local elastic deformation on the sliding velocity has been separately investigated.

  • 45.
    Enblom, Roger
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Stichel, Sebastian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Industrial implementation of novel procedures for the prediction of railway wheel surface deterioration2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, nr 1-2, s. 203-209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adequate performance of the wheel-rail interface is essential for satisfactory operation of a railway system in terms of quality of service and maintenance effort. Pertinent requirements on efficiency tend to push the operation conditions towards higher loads and increased speed while the wheel-rail contact remains a small and highly stressed area. Dominating modes of deterioration due to high normal and tangential stresses are wear and rolling contact fatigue. Both kinds lead to surface material loss, in the former case as a slow rate profile geometry change with consequences to the dynamic performance and in the latter case different crack patterns and eventually spalling or shelling requiring reprofiling. In this paper the implementation of emerging technologies for the prediction of wheel surface deterioration in an engineering environment is summarised. Methods for the prediction of wear and profile geometry evolution as well as for the assessment of the risk for the onset of rolling contact fatigue are described. Example results from recent applications are given. In general it may be concluded that the implemented methods are becoming useful for the prediction of profile alterations, for instance hollow wear linked to conicity increase, and flange wear. The fatigue assessment methods are less mature and need further calibration but are still capable of indicating location and significance of risk for damage.

  • 46.
    Eriksson, Mikael
    et al.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory.
    Lord, John
    Jacobson, Staffan
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory.
    Wear and contact conditions of brake pads: dynamical in situ studies of pads on glass2001Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 249, nr 3-4, s. 272-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A pin-on-disc machine has been used to make in situ observations of the dynamics of the contact between brake pad materials and a glass disc, while simultaneously monitoring the friction force. The machine, that is normally used to study elastohydrodynamical film formation, has been slightly modified and fitted with a brake pad material sample instead of a rolling ball. The glass disc facilitates direct microscopy and video recording of the dynamic contact situation using a microscope equipped with a CCD-camera. The most obvious features of the topography of a brake pad are the contact plateaus, small flat islands rising typically a few microns above the rest of the surface. These plateaus are based on the more wear resistant constituents of the pad such as fibres and abrasive particles, but also include softer ingredients. The study shows that the softer and more porous areas surrounding the contact plateaus are worn mainly through three-body abrasion. When the disc is sliding against the plateaus, a large number of small particles (wear debris) are transported through the narrow labyrinth between the surfaces, milling down the weaker constituents. The wear debris can also form very small particles or a continous friction film that may become compacted in front of the initial contact plateaus based on, e.g. a metal fibre. In this way larger but softer plateaus form. The investigation elucidates the rapid changes of the contact situation on a microscale.

  • 47.
    Fallqvist, M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Olsson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Influence of CVD Al2O3 coated tool surface micro topography on the tribological characteristics in metal cutting – Part I2012Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577Artikel i tidskrift (Refereegranskat)
  • 48.
    Fallqvist, M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Olsson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Influence of CVD Al2O3 coated tool surface micro topography on the tribological characteristics in metal cutting – Part II2012Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577Artikel i tidskrift (Refereegranskat)
  • 49.
    Fallqvist, Mikael
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    The influence of surface defects on the mechanical and tribological properties of VN-based arc-evaporated coatings2013Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 297, nr 1-2, s. 1111-1119Artikel i tidskrift (Refereegranskat)
    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.

  • 50.
    Fallqvist, Mikael
    et al.
    Högskolan Dalarna, materialvetenskap.
    Olsson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    The influence of surface defects on the mechanical and tribological properties of VN-based arc-evaporated coatings2013Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 297, nr 1-2, s. 1111-1119Artikel i tidskrift (Refereegranskat)
    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 system.

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