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  • 51.
    Lu, Xinyu
    et al.
    Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-forest biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
    Gu, Xiaoli
    Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-forest biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    A review on the synthesis of MXenes and their lubrication performance and mechanisms2023In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 179, article id 108170Article, review/survey (Refereed)
    Abstract [en]

    MXenes (MXs), as an emerging 2D family of transition metal carbides and nitrides, have been considered as new candidates for solid lubrication/lubricant additives due to their mono-layered graphene-like structure with similar mechanical properties, abundant surface terminations (i.e., -O, -OH, -F), relatively low shear strength and inherent self-lubrication ability. In this review, we introduced MXs’ synthesis and their lubrication performance and mechanisms. Typically, pure MXs and MXs-based composites like MXs/polymers, MXs/graphene (MoS2) or MXs/metals (metal oxide) were used as reinforcement materials to form protective coatings with excellent mechanical properties and solid lubrication performance. As liquid lubricant additives, MXs can be used as water-/oil-based lubricant additives, and exhibit improved friction and wear. At the same time, chemically functionalized MXs with better dispersibility and compatibility were introduced as the improved oil-based lubricant additives. Some parameters (such as MXs’ structural effects and working conditions) affecting MXs’ lubrication performance, and the lubrication mechanisms (such as the formation of tribofilm, the hydrophilicity-/interlayer-dependent lubrication mechanism and adsorption effect) were all discussed. Finally, some future perspectives for MXs’ lubrication were proposed at the end of this review.

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  • 52.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Influence of surface roughness on normal-sliding lubrication1995In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 28, no 5, p. 317-322Article in journal (Refereed)
    Abstract [en]

    Contact between machine components can involve normal, sliding and rolling motion, either singly or in combination. Combined normal and sliding motion, which occur for example in the meshing of gear teeth and in heavily-loaded rolling elements, can present problems for lubrication. The purpose of the present experimental study was to investigate how surface roughness affects the lubricant film characteristics under conditions of combined normal and sliding motion. The experimental arrangement consisted of a rotating roller which impacted a stationary ball in the presence of a lubricant. Under the same conditions of normal surface approach, increasing the surface roughness significantly decreased the level of roller sliding that could occur without breakdown of the lubricating film. This behaviour was similar to a step function. Of the several surface roughness parameters investigated, only those which involved the maximum peak-to-valley height correlated well with experimental results. In general, surface roughness had a greater effect on oil film breakdown than did either viscosity or load.

  • 53. Lundberg, Jan
    et al.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    A new method for determining the mechanical stability of lubricating greases2000In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 33, no 3-4, p. 217-223Article in journal (Refereed)
    Abstract [en]

    Mechanical stability is of central importance when dealing with the long-term service-length of grease-lubricated roller bearings. Poor stability will lead to consistency degradation of the grease, because of mechanical forces between the rolling parts of the bearing. The result can be leakage of grease through seals, or at worst a total failure of the bearing. The present investigation was initiated because present-day methods for prediction of mechanical stability show weak correlation with real service-length. The aim of the project was to develop a useful alternative. In order to fulfil this, both field tests and laboratory tests were carried out. In the field tests, nine different commercial greases were examined in the wheel bearings of five ore waggons, used for transporting ore by railroad from the Kiruna Mine in northern Sweden to Narvik in northern Norway for shipping to foreign markets. The test ore waggons travelled a distance of about 300,000 km during a period of 3 years. Small samples of greases were taken, on eight different occasions, for consistency testing. After the end of the test period, the damage on the bearings was also studied. In the laboratory tests, new undestroyed greases of the same brand as in the field tests were examined using conventional methods, such as the V2F, the Roll Stability Test and the Grease Worker. Comparisons between the field tests and these laboratory tests indicate poor correlation. In addition to these conventional methods, the relevance of the shear strength of the greases to the prediction of the mechanical stability was also tested. The shear stress τL depends on the applied pressure p, thus τL=τO+γ·p where τO is the shear stress at atmospheric pressure, γ is a property of the lubricant in the same way as viscosity or density. It was found that γ correlates well with the mechanical stability in service. Increased γ values lead to a decrease in the mechanical stability. One reasonable explanation is that high γ values correspond to high shear stresses in the grease, and thus severe conditions for the thickener.

  • 54.
    Markin, D.
    et al.
    Luleå University of Technology.
    McCarthy, Donald M.C.
    Luleå University of Technology.
    Glavatskih, Sergei B.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    A FEM approach to simulation of tilting-pad thrust bearing assemblies2003In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 36, no 11, p. 807-814Article in journal (Refereed)
    Abstract [en]

    Finite-element method (FEM) modelling is applied to analysis of the performance of hydrodynamic tilting-pad thrust bearing assemblies. A 3D model of the bearing assembly that includes the bearing pad and shaft is used to assess the influence of operating conditions on bearing parameters such as temperature and oil film distributions across the pads. The model is first applied to the investigation of a spherically pivoted-pad. Through comparison with results from experiments carried out on just such a bearing, good correlation between the model and experimental results is found for maximum oil film temperature, pressure distribution and thickness. The model is then applied to the examination of a bearing having spring-supported babbitt pads. The effect of different oil types on a spring-supported thrust bearing is analysed. Further application of the model to investigate the same spring-supported pad, this time with a resilient surface coating, is discussed.

  • 55. Marklund, Pär
    et al.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Wet clutch friction characteristics obtained from simplified pin on disc test2008In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 41, no 9-10, p. 824-830Article in journal (Refereed)
    Abstract [en]

    The frictional behavior of wet clutches in vehicle drivetrains is critical for their overall behavior. During the development of new wet clutch systems there is a need to know this friction behavior. The transferred torque is normally investigated in test rigs where the friction in a sliding interface between a friction disc and separator disc is investigated. These test rigs can be designed differently, depending on the working conditions of the investigated clutch. However, it is possible today to simulate the clutch behavior and not limit ourselves to only using measurements from test rigs for the design of the wet clutch. The torque transferred by the clutch during engagement can be roughly divided into full film torque and boundary lubrication torque. The full film regime is possible to simulate quite well, whereas the friction in the boundary regime is much more difficult to simulate due to its strong additive dependency. To obtain a good prediction of the total engagement, friction measurements in the boundary lubrication regime are still needed. These measurements should be easy to perform and fast tests are preferable. Friction coefficients for the whole range of sliding speed, interface temperature and nominal surface pressure should be measured. To use these measurements in simulations and get a better understanding of the friction behavior, it is also preferable to conduct these measurements on a small test sample, for which the temperature and sliding speed can be regarded as constant.Here, the friction of a small sample of a wet clutch friction disc is investigated in a pin on disc test and the temperature is measured in the sample during the tests. Measurements are compared with measurements from a test rig for whole friction discs. A good correspondence between the frictional behaviors of the different measurement methods is achieved.

  • 56.
    Marklund, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Mäki, Rikard
    Larsson, Roland
    Höglund, Erik
    Khonsari, M.M.
    Louisiana State University.
    Jang, Joonyoung
    Louisiana State University.
    Thermal influence on torque transfer of wet clutches in limited slip differential applications2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 5, p. 876-884Article in journal (Refereed)
    Abstract [en]

    Wet clutches operating under low velocity and high load are studied with the aim of obtaining reliable models for the torque transfer during boundary lubrication conditions. A friction model which takes temperature, speed and nominal pressure into account is developed and used with temperature calculations to be able to simulate behavior of a wet clutch working in boundary lubrication regime. Predicted torque and temperatures from the model agree well with experimental data.

  • 57.
    Martin del Campo Barraza, Sergio
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Schnabel, Stephan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Detection of particle contaminants in rolling element bearings with unsupervised acoustic emission feature learning2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 132, p. 30-38Article in journal (Refereed)
    Abstract [en]

    The detection of contaminants in the lubricant of rolling element bearings using acoustic emission signals is a challenging problem, in particular at high rotational speeds. This problem calls for new analysis methods beyond the conventional amplitude- and frequency-based methods. Feature learning is successfully used in the machine learning field to characterize complex signals. Here we use an unsupervised feature learning approach to distinguish acoustic emission signals. We investigate the repetition rates of features identified with shift-invariant dictionary learning and find that the signature of contaminated lubricant is significantly stronger than the effect on conventional condition indicators like the RMS and the enveloped RMS at rotational speeds above 300 rpm and up to 3000 rpm.

  • 58.
    Mofidi, Mohammad
    et al.
    Luleå University of Technology.
    Kassfeldt, Elisabet
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Prakash, Braham
    Luleå University of Technology.
    Tribological behaviour of an elastomer aged in different oils2008In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 41, no 9-10, p. 860-866Article in journal (Refereed)
    Abstract [en]

    This paper presents the influence of aging the nitrile rubber, the most popular seal material, in various base fluids on sliding friction and abrasive wear. The lubricants used are synthetic esters, natural esters, different types of mineral base oils, poly-*-olefins and very high viscosity index oils. Friction has been studied for two directions of motion with respect to lay on the elastomer sample by using the SRV Optimol test machine. These findings show that as compared to all other lubricant formulations, ageing the elastomer in polyol ester leads to the maximum reduction of friction coefficient especially in perpendicular sliding to the initial lay on the surface. The abrasive wear studies were carried out by using a two-body abrasive wear tester against dry and lubricated elastomer. It was interesting to note that two-body abrasive wear of elastomeric material was higher during rubbing in presence of the fluids as compared to that in dry condition. Further, aging the elastomer in these base fluids especially in ester base fluids, results in more abrasive wear.

  • 59.
    Moghaddam, P. Valizadeh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hardell, Jens
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China.
    Effect of retained austenite on adhesion-dominated wear of nanostructured carbide-free bainitic steel2020In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 150, article id 106348Article in journal (Refereed)
    Abstract [en]

    Sliding wear performance of carbide-free bainitic steel is significantly affected by microstructure. This investigation is an attempt to find a correlation between microstructure and wear resistance of carbide-free bainitic steel and compare the results with that of a conventional tempered martensitic microstructure. Under predominantly adhesive wear conditions, carbide-free bainitic microstructure with the highest amount of retained austenite offers the best wear resistance. This is mainly attributed to the more pronounced work hardening and TRIP-effect of carbide-free bainitic microstructure austempered at higher temperature. Therefore, higher initial bulk hardness is not the only indicator of wear resistance. Moreover, when both oxidation and adhesion are active, a microstructure with an optimum content of retained austenite and bainitic ferrite shows the highest wear resistance.

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  • 60.
    Moghaddam, Pouria Valizadeh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Fallqvist, Mikael
    SECO Tools AB, Fagersta, SE-737 82 Sweden.
    Andersson, Jon M.
    SECO Tools AB, Fagersta, SE-737 82 Sweden.
    Hardell, Jens
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    High temperature tribology of TiAlN PVD coating sliding against 316L stainless steel and carbide-free bainitic steel2021In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 159, article id 106847Article in journal (Refereed)
    Abstract [en]

    Reciprocating sliding wear tests were performed on TiAlN coating against 316L stainless steel and carbide-free bainitic steel at temperatures of 40, 400 and 800 oC. The results indicate that material transfer is more pronounced for the softer stainless steel at lower temperatures but at 800 oC, carbide-free bainite exhibits relatively more material transfer. Friction coefficient of stainless steel increases when temperature increases. However, for carbide-free bainite, there is a reduction in friction coefficient at elevated temperatures. This can be attributed to formation of an easily sheared iron oxide layer at elevated temperatures. In case of stainless steel, generation of a thin tribofilm containing aluminium oxide and oxidised transferred material can protect the TiAlN coating against wear at 800 oC.

  • 61.
    Nikonovich, Maksim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. CEMMPRE, Department of Mechanical Engineering, University of Coimbra, Portugal.
    Ramalho, Amilcar
    CEMMPRE, Department of Mechanical Engineering, University of Coimbra, Portugal.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Effect of cryogenic aging and test-environment on the tribological and mechanical properties of PEEK composites2024In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 194, article id 109554Article in journal (Refereed)
    Abstract [en]

    This study investigated mechanical and tribological properties of polyetheretherketone (PEEK) and PEEK composites, before and after aging in liquid nitrogen for 5 months. Tribological tests conducted at 25 °C and at − 100 °C in air and in high vacuum (10−5 Pa) environment revealed the effect of matrix modification, fillers, environment, temperature, and cryogenic aging on their performances. Cryogenic aging of the polymers resulted in cryogenic embrittlement and decrease of the fracture toughness by around 10% and increase of wear rate by at least 20%. Very low coefficient of friction (0.02) was achieved in cryogenic vacuum environment for carbon fiber, graphite, and PTFE reinforced PEEK. The results indicate the significant impact of aging, temperature and environment on PEEK and its composites.

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  • 62. Nilsson, Daniel
    et al.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Investigation into the seizure of hydraulic motors2010In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 43, no 1-2, p. 92-99Article in journal (Refereed)
    Abstract [en]

    Despite its practical significance, the occurrence of seizure in tribological systems has not been fully understood. In this work, extensive actual tests on hydraulic motors under extreme operating conditions of low viscosity, high pressure and speed have been conducted with a view to investigate and understand the seizure mechanism. Some of the motors failed and they were stopped at different stages of progressive seizure. Based on these investigations, a three stage seizure process has been suggested. Stage 1 involves the breakdown of hydrodynamic oil film between roller and piston which leads to increased friction, thermal expansion and increased leakage. In stage 2, scuffing is initiated either between roller and piston or between piston and cylinder. During stage 3 scuffing propagate to several pistons.

  • 63.
    Olsson, Håkan
    et al.
    ITH, The Institute for Applied Hydraulics, Örnsköldsvik, Sweden.
    Ukonsaari, Jan
    Luleå University of Technology.
    Wear testing and specification of hydraulic fluid in industrial applications2003In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 36, no 11, p. 835-841Article in journal (Refereed)
    Abstract [en]

    The aim of this paper was to investigate the possibilities to use a model test to simulate the wear between cylinder bore and piston in a radial piston hydraulic motor. The tests were performed in a reciprocating test rig where the contact geometry is of the cylinder-plate type. The influence of different types of commercially available hydraulic fluids on wear protection and friction was studied. From the study, it was concluded that the use of water glycols can cause increased wear in hydraulic motors operating in low speed applications. It was also seen that the FZG test alone appears not to be enough as a hydraulic fluid wear test, at least not in the tribological conditions present in the performed wear test.

  • 64.
    Palmeira Belotti, Luca
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Vadivel, Hari Shankar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological performance of hygrothermally aged UHMWPE hybrid composites2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 138, p. 150-156Article in journal (Refereed)
    Abstract [en]

    In this work, the effect of hygrothermal aging on friction and wear of water lubricated, Ultra High Molecular Weight Polyethylene (UHMWPE) hybrid composites were evaluated. Graphene Oxide (GO), Nano Diamonds (ND) and Short Carbon Fibers (SCF) were used as reinforcements as they previously exhibited promising improvements in the tribological behavior of UHMWPE in water-lubricated sliding contacts. Hygrothermal aging and pin-on-disc tribological experiments were performed to evaluate the response of the UHMWPE composites. It was observed that the friction and wear of the composites were not significantly affected by the aging conditions, which was attributed to the structural integrity of the newly developed UHMWPE based hybrid composites.

  • 65.
    Pelcastre, Leonardo
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hardell, Jens
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Galling mechanisms during interaction of tool steel and Al-Si coated ultra-high strength steel at elevated temperature2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 67, p. 263-271Article in journal (Refereed)
    Abstract [en]

    Occurrence of galling in hot forming is detrimental to the quality of produced parts and process economy. Material transfer from Al-Si coated work-piece to the tool material has been studied in this work. PVD coatings (AlCrN, TiAlN and DLC) on tool steel substrate have been considered as well as plasma nitriding and their tribological behaviour was compared to the case of an untreated tool steel. Galling initiates through accumulation and compaction of wear debris when untreated tools are used whereas the PVD coatings resulted in increased galling due to adhesion. Plasma nitrided tool steel showed negligible galling due to formation of glaze layers and the formation of such layers depends on the occurrence of wear of the nitrided tool steel.

  • 66.
    Pettersson, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    High-performance base fluids for environmentally adapted lubricants2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 4, p. 638-645Article in journal (Refereed)
    Abstract [en]

    Future lubricants have to be more environmentally adapted, have a higher level of performance, and lower total life cycle cost (LCC) than presently used lubricants. To be able to formulate those lubricants, the properties of the base fluids have to be well known. Base fluid properties that influence the formulated lubricant performance could be divided into three different groups. These groups are: physical, chemical, and film formation properties. In this study, properties from all of these groups are investigated to improve the understanding on thier influence on base fluid overall performance. There are more or less environmentally adapted base fluids available for formulation of lubricants. They could be divided into different groups, mineral, semi-synthetic, and synthetic fluids. Synthetic fluids could be of different types: polyalpha olefins (PAO), synthetic ester, polyglycols, and others. The most interesting group for formulation of environmentally adapted lubricants are the synthetic esters. In this study, the properties for a large number of environmentally adapted ester base fluids are studied in detail. The tested properties relate to the macroscopic/molecular behavior and include: viscosity-temperature-pressure effects, η(p,T) , thermal conductivity, λ(p,T), and heat capacity per unit volume, pcp(p,T) . The film formation capability in elasto-hydrodynamic contacts is also studied. Different connections between the molecular structure and the performance of the fluids are discussed. As an example, it is found that a large number of carboxylate groups in the ester molecule improve the thermal properties, and thereby a thicker lubricating film could be maintained in highly loaded, high-slip contacts.

  • 67.
    Pettersson, Anders
    Luleå University of Technology.
    Tribological characterization of environmentally adapted ester based fluids2003In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 36, no 11, p. 815-820Article in journal (Refereed)
    Abstract [en]

    Fundamental properties of six synthetic ester base fluids, suitable for the formulation of environmentally adapted lubricants, have been investigated. High pressure viscosity data for the test fluids were obtained through experimental measurements with a high pressure Couette rheometer. The temperature, pressure and viscosity data η(p, T) were parameterized against the Roelands pressure-viscosity equation. Thermal conductivity and specific heat capacity data were obtained using a transient hotwire method, and the EHD friction coefficient, γ, was obtained experimentally as well. The results from these measurements are reported, and the correlation between thermal properties, molecular structure, and the fluid rheology parameters, of the test fluids are discussed.

  • 68.
    Rafols, Francesc Perez
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Modelling of leakage on metal-to-metal seals2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 94, p. 421-427Article in journal (Refereed)
    Abstract [en]

    Surfaces in a typical seal exhibit both waviness and roughness. The influence of the interaction between these two scales on the leakage behaviour is expected to be relevant. Therefore, a model, which can study it, is developed here. The model is composed of state-of-the-art models for the contact mechanics between rough metal surfaces and for the liquid flow through the rough aperture in-between them. Correlation between percentage real contact area and actual contact topology and leak rate was confirmed through numerical analysis. Small changes in relative position between the contacting surfaces showed large deviation in leak rate. The validity of the model was justified by comparing results from numerical simulations using the model and experimental results found in literature qualitatively.

  • 69.
    Raposo, Hugo
    et al.
    Coimbra University-UC, Department of Mechanical Engineering, Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Coimbra, Portugal.
    Torres Farinha, José
    Coimbra University-UC, Department of Mechanical Engineering, Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Coimbra, Portugal.
    Fonseca, Inácio
    Coimbra University-UC, Department of Mechanical Engineering, Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Coimbra, Portugal.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Predicting condition based on oil analysis: A case study2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 135, p. 65-74Article in journal (Refereed)
    Abstract [en]

    The paper presents and discusses a model for condition monitoring. Using data from the oil in the Diesel engines of a fleet of urban buses, it studies the evolution of degradation and develops a predictive maintenance policy for oil replacement. Based on the analysis of the oil condition, the intervals of oil replacement can be expanded, allowing increased availability. The paper links time series forecasting with the statistical behavior of some oil effluents, like soot. This exercise can be expanded to include other variables, and the model has the potential to be applied to other physical assets to achieve the best availability based on a condition monitoring policy.

  • 70.
    Rohlmann, Patrick
    et al.
    Department of Engineering Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden.
    Black, Jeffrey J.
    School of Chemistry, University of New South Wales, Sydney NSW 2052, Australia.
    Watanabe, Seiya
    Surface and Corrosion Science, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Leckner, Johan
    Department of Engineering Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden; Axel Christiernsson International AB, SE-44911 Nol, Sweden.
    Shimpi, Manishkumar R.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Rutland, Mark W.
    School of Chemistry, University of New South Wales, Sydney NSW 2052, Australia; Surface and Corrosion Science, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; Laboratoire de Tribologie et de Dynamique des Systèmes, Ecole Centrale de Lyon, 69134 Ecully, France.
    Harper, Jason B.
    School of Chemistry, University of New South Wales, Sydney NSW 2052, Australia.
    Glavatskih, Sergei
    Department of Engineering Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney NSW 2052, Australia; Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium.
    Tribochemistry of imidazolium and phosphonium bis(oxalato)borate ionic liquids: Understanding the differences2023In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 181, article id 108263Article in journal (Refereed)
    Abstract [en]

    Lubrication properties of imidazolium and phosphonium bis(oxalato)borate ionic liquids (ILs) are compared in a reciprocating sliding contact at 80 °C and 140 °C. Both the influence of the alkyl chain length and the cation architecture on friction, wear and lubricant breakdown are investigated. Imidazolium ILs showed lower friction than phosphonium ILs though only phosphonium-based ILs reduced wear. A longer alkyl chain reduced friction only in the case of the imidazolium-based ILs. Analysis of the wear scars was consistent with chemical breakdown solely of the anion. Chemical changes in the ILs after the tribotests were more pronounced for imidazolium-based ILs, and comparison of breakdown and tribofilm formation implicated catalysis by the imidazolium center, which, in turn, had a strong dependence on the surface self-assembly.

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  • 71.
    Rohlmann, Patrick
    et al.
    Department of Machine Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Watanabe, Seiya
    Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
    Shimpi, Manishkumar R.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Leckner, Johan
    Axel Christiernsson International AB, SE-44911 Nol, Sweden.
    Rutland, Mark W.
    School of Chemistry, University of New South Wales, UNSW Sydney NSW 2052, Australia; Division of Surface and Corrosion Science, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, SE-100 44 Stockholm, Sweden.
    Harper, Jason B.
    School of Chemistry, University of New South Wales, UNSW Sydney NSW 2052, Australia.
    Glavatskih, Sergei
    Department of Machine Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, SE-100 44 Stockholm, Sweden; Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium.
    Boundary lubricity of phosphonium bisoxalatoborate ionic liquids2021In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 161, article id 107075Article in journal (Refereed)
    Abstract [en]

    The lubricating performance of trihexyl(tetradecyl)phosphonium bis-(oxalato)-orthoborate (P-BOB) ionic liquid is analysed at 80°C and 140°C, together with an ionic liquid containing partially hydrated version of the anion. The reduction of the anions produces oxalate complexes that contribute synergistically to lower friction. To confirm the role of oxalate in enhancing lubricity, two ionic liquids, at different stages of the synthesis were used. One of the batches contained precursor orthoborate anions complexed with oxalic acid and consequently showed the lowest friction at 80°C. Upon heating the precursor was converted into [BOB]- and displayed the same friction at 140°C as the fully synthesised species. The mechanisms of the breakdown of the [BOB]- anion and formation of the tribofilm are elucidated.

  • 72.
    Ràfols, Francesc Pérez
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Generating randomly rough surfaces with given height probability distribution and power spectrum2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 131, p. 591-604Article in journal (Refereed)
    Abstract [en]

    In this work we present a simple method to generate surface topography. The main advantage of the presented method as compared with those available in the literature is that the power spectrum and the height probability distribution can be specified independently. In this article we present the method and show its versatility by generating surface topographies with three different height probability distributions: the Weibull distribution, a bimodal distribution and a distribution containing a delta function that represents worn surfaces. The MATLAB-code we used to generate the numerical examples are also provided to the reader.

  • 73. Sahlin, Fredrik
    et al.
    Almqvist, Andreas
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Glavatskih, Sergei
    A cavitation algorithm for arbitrary lubricant compressibility2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 8, p. 1294-1300Article in journal (Refereed)
    Abstract [en]

    A general cavitation algorithm that accommodates for an arbitrary density-pressure relation is presented. It is now possible to model the compressibility of the lubricant in such a way that the density-pressure relation is realistic throughout the contact. The algorithm preserves mass continuity for cavitation caused by bearing geometry and surface topography. It is a commonly accepted physical assumption that the contribution of the pressure driven flow is negligible in the cavitated region. This phenomenon is adopted in the present algorithm, which is similar to that of Elrod, and is modeled by a switch function that terminates the pressure gradient at the cavitation regions. Results with this algorithm for different density-pressure relations are presented and discussed. The effects of inlet conditions, such as surface roughness and starvation, on the load carrying capacity of the contact are analyzed.

  • 74.
    Sahlin, Fredrik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Glavatskih, Sergei
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Rough surface flow factors in full film lubrication based on a homogenization technique2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 7, p. 1025-1034Article in journal (Refereed)
    Abstract [en]

    This paper describes a method to compute the flow factors that compensate for an arbitrary surface roughness in a compressible hydrodynamic lubrication based on a homogenization technique. The Reynolds equation is used as the governing equation and the two-scale expansion involved in the homogenization process enables the local roughness scale to be treated separately from the global geometry scale. With this method, it is possible to compute the flow factors for any deterministic roughness. Measured two-dimensional surface profiles are used as examples. Profiles having the same Abbot curve are also shown to have the same flow factors, providing an efficient classification of surfaces in hydrodynamic two-dimensional contacts. Flow factors are computed for the rough surface profiles, and solutions for global bearing geometry are obtained and compared with the corresponding solutions from a smooth geometry.

  • 75.
    Schnabel, Stephan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Golling, Stefan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    The Detection of Plastic Deformation in Rolling Element Bearings by Acoustic Emission2017In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 110, p. 209-215Article in journal (Refereed)
    Abstract [en]

    The detection of plastic deformation caused by particle contamination in rolling element bearings using acoustic emission is reliable at low speeds as shown in several studies. However, there are no studies at greater speeds of the detection of plastic deformation by acoustic emission in rolling element bearings. The acoustic emission signals of rolling element bearings have, however, been shown to be dominated by transient force signals which are elastic waves caused by transient forces acting at the raceway surface. The results of the test showed a dominance of transient force signals at elevated speeds, which masks signals caused by plastic deformation and prohibits the detection of particle contamination, while at low rotational speed plastic deformation is detected by acoustic emission.

  • 76.
    Shi, Yijun
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Minami, Ichiro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Björling, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Boundary and elastohydrodynamic lubrication studies of glycerol aqueous solutions as green lubricants2014In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 69, p. 39-45Article in journal (Refereed)
    Abstract [en]

    In this paper, the boundary and elastohydrodynamic lubricating behaviour of glycerol and its aqueous solutions are discussed in both rolling and sliding contacts with a view on assessing the use of glycerol as a green lubricant. To understand the lubricating mechanism, the film thickness of glycerol and its aqueous solutions were studied at different velocities. The results show that the viscosity of glycerol can be controlled for a wide range by adding different amounts of water. The lubricating behaviour of glycerol in all lubricating regimes can be improved by adding water. The results suggest that glycerol aqueous solutions have great potential to replace rapeseed oils as environmentally friendly base oils in several applications.

  • 77.
    Shirzadegan, Mohammad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Fully coupled EHL model for simulation of finite length line cam-roller follower contacts2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 103, p. 584-598Article in journal (Refereed)
    Abstract [en]

    This paper presents a fully coupled multiphysics model developed for numerical simulation of the elastohydrodynamically lubricated contact between a cam and roller, typically found in cam mechanisms controlling fuel injection in an internal combustion engine. Special attention was focused on enabling systematic analyses of effects associated with, roller crowning and edge geometries, lubricant rheology as well as typical cam mechanism operating conditions. The interaction between the cam and roller follower result in high generated pressure and narrow film thickness that increase the risk of wear and fatigue. Furthermore, this article highlights the variation of pressure and film thickness under tilting conditions. The model was also validated against some particular model problems, found in the literature.

  • 78.
    Shirzadegan, Mohammad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Björling, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Low degree of freedom approach for predicting friction in elastohydrodynamically lubricated contacts2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 94, p. 560-570Article in journal (Refereed)
    Abstract [en]

    A low degree of freedom, semi-analytical model for rapid estimation of the friction coefficient in elastohydrodynamically lubricated contacts was developed and tested. Its estimates are based on the shear rate dependent Carreau equation for the apparent viscosity, together with the hydrodynamic pressure and the temperature of the lubricant. To validate the approach, the model's predictions were compared to experimental coefficient of friction measurements acquired using a ball-on-disc test device at various applied loads, entrainment velocities, and slide to roll ratios. The model’s predictions were in good agreement with the experimental results, showing that it is suitable for use in multibody dynamics analyses where rapid computation of elastohydrodynamic friction is required to minimize computing time and resource consumption.

  • 79.
    Shirzadegan, Mohammad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    A low degree of freedom approach for prediction of friction in finite EHL line contacts2017In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 115, p. 628-639Article in journal (Refereed)
    Abstract [en]

    A low degree of freedom (LDOF) approach for expedient prediction of friction in finite EHL line contact is presented. Friction prediction are in good agreement with existing results for all of the reference cases tested. With the present LDOF approach, friction predictions can be obtained thousands of times faster than if using a fully coupled FE-based model. It can, therefore be used to simulated the tribological contacts in multi-body dynamic (MBD) systems with millions of degrees of freedoms. The model was utilised to study edge stress concentrations due to roller tilt. The results confirmed that increasing the tilting angle increases the maximum pressure and shifts its location towards the edge of roller. An increase in total friction was also observed.

  • 80.
    Simmons, Gregory F.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. LKAB, Kiruna 98186, Sweden.
    Cerda Varela, Alejandro
    Department of Mechanical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
    Ferreira Santos, Ilmar
    Department of Mechanical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
    Glavatskihi, Sergei
    Machine Design, Royal Institute of Technology, 10044 Stockholm, Sweden; Department of Mechanical Construction and Production, Ghent University, Ghent, Belgium.
    Dynamic characteristics of polymer faced tilting pad journal bearings2014In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 74, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Dynamic characteristics of polymer faced tilting pad journal bearings are presented. Investigations are conducted using a single pad, load on pad configuration over a range of shaft speeds and loads. Two polyether ether ketone (PEEK) faced pads, one polytetrafluoroethylene (PTFE) faced pad and two entirely PEEK pads are investigated to determine the effect of varying mean bearing pressure and pivot characteristics as well as different material properties of the polymer layer. Experimental results indicate increased damping and decreased stiffness and slightly increased oil film temperature for entirely PEEK pads compared to pads with a PEEK lining and steel backing. Similar effects were observed by using a softer (PTFE) pad liner with a steel backing.

  • 81.
    Simmons, Gregory F
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Glavatskih, Sergei
    Machine Design, Royal Institute of Technology.
    Mûller, Michael
    Evonik RohMax Additives GmbH, 64293 Darmstadt.
    Byheden, Åke
    Statoil Lubricants, Nynäshamn.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Extending performance limits of turbine oils2014In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 69, p. 52-60Article in journal (Refereed)
    Abstract [en]

    New turbine oils providing both extremely high viscosity index (VI) and improved boundary/mixed lubrication performance are investigated. Comparisons are made in both laboratory scale testing using typical journal bearing sliding surfaces (steel and white metal) and full scale testing using a hydrodynamic journal bearing test machine. The results from these studies demonstrate the effectiveness of new, high VI, turbine oils for reducing friction at machine startup and improving performance during full film operation.

  • 82.
    Sin, Jorge Rituerto
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Suñer, Silvia
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Neville, A.
    Institute of Engineering Thermofluids, Surfaces and Interfaces, School of Mechanical Engineering, University of Leeds, LS2 9JT Leeds, UK.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Fretting corrosion of Hafnium in Simulated Body Fluids2014In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 75, p. 10-15Article in journal (Refereed)
    Abstract [en]

    Hafnium has been suggested as an interesting material for biomedical applications due to its good biocompatibility and osteogenesis. However, its behaviour under fretting corrosion conditions, found in applications such as dental and joint implants, has not been studied in depth. A three-electrode electrochemical cell integrated with a ball-on-flat reciprocating tribometer was used to investigate the corrosion of hafnium and commercially pure (CP) titanium in simulated body fluids. An increased susceptibility to pitting corrosion was observed when hafnium was subjected to fretting. Open circuit potential measurements showed a more severe mechanical depassivation due to fretting in the case of CP titanium in comparison to hafnium. In addition, the anodic currents measured during potentiostatic tests were also higher for CP titanium.

  • 83.
    Somberg, Julian
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Gonçalves, Gil
    Centre for Mechanical Technology and Automation (TEMA), University of Aveiro, Portugal; Intelligent Systems Associate Laboratory (LASI), Portugal.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Graphene oxide versus graphite and chemically expanded graphite as solid lubricant in ultrahigh molecular weight polyethylene composites2023In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 187, article id 108643Article in journal (Refereed)
    Abstract [en]

    Graphene oxide (GO), chemically expanded graphite (CEG) and graphite were evaluated as solid lubricant for ultrahigh molecular weight polyethylene composites. Under dry conditions, the addition of all solid lubricants increased the coefficient of friction by up to 38%. For the composites corrugated stick–slip features were observed which correlate with a decrease in matrix degree of crystallinity. GO had the lowest effect on the crystallisation, resulting in the lowest relative increase in friction coefficient of only 13%. Under water lubrication, GO, CEG and graphite were equally effective in reducing friction and wear. The highest friction for the neat matrix was found to be due to a transfer film, which was suppressed by the addition of the solid lubricants.

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  • 84.
    Somberg, Julian
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Saravanan, Prabakaran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Vadivel, Hari Shankar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Berglund, Kim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. Sustainalube AB, Sweden.
    Ukonsaari, Jan
    Vattenfall AB, R&D, Sweden.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological characterisation of polymer composites for hydropower bearings: Experimentally developed versus commercial materials2021In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 162, article id 107101Article in journal (Refereed)
    Abstract [en]

    To mitigate the effects of downstream lubricant spillage from hydroelectric power plants, environmentally friendly lubricants are required. For the sustainable operation of oil-free bearings, the development of high performance bearing materials is crucial. In this study, the tribological performance of PPS and UHMWPE-based composites, incorporating various reinforcements, such as graphene oxide, is evaluated and compared with five commercial materials. Experiments were performed under different lubricating conditions; Dry, water, and using a glycerol-based environmentally adaptive lubricant (EAL). The use of water inhibited an adequate transfer film, which increased wear for most materials. EAL lubrication showed a significant reduction in friction (up to 98%) when compared to dry conditions. The experimentally developed PPS composite provided superior tribological properties, especially under water-lubricated conditions.

  • 85.
    Spencer, Andrew
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Dobryden, Illia
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Almqvist, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    The influence of AFM and VSI techniques on the accurate calculation of tribological surface roughness parameters2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 57, p. 242-250Article in journal (Refereed)
    Abstract [en]

    Vertical Scanning Interferometry (VSI) may induce optical artefacts in surface topography measurements. The influence of these optical artefacts on the calculation of Rk surface roughness parameters, contact stiffness and flow factors were studied. Two surface measurement techniques were used: Atomic Force Microscopy (AFM) and VSI. Calibration grids were used to make it easier to isolate the causes of these artefacts, while a real engineering surface was used to compare these two techniques in an industrially applied case. It was found that the optical artefacts have a large influence on all the roughness parameters, contact stiffness and flow factors calculated on the calibration grids. However, for the engineering surface the differences between AFM and VSI measurements were much smaller.

  • 86.
    Strömbergsson, Daniel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Edin, Emil
    Applied Nano Surfaces Sweden AB.
    Zeman, Frida
    Applied Nano Surfaces Sweden AB.
    Acoustic emission monitoring of a mechanochemical surface finishing process2017In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 112, p. 129-136Article in journal (Refereed)
    Abstract [en]

    Acoustic emission monitoring of cutting machining operations is an established researched area, though monitoring non-removal finishing processes is less studied.

    This work presents an initial investigation on Acoustic emissions potential of an mechanochemical superfinishing process. Conclusions are drawn from the monitoring signal regarding the resulting surface friction characteristics, composition and possible runnability issues.

    Monitoring data was collected from tests performed at Applied Nano Surfaces' testing laboratory. Test series with varying parameters enabled a correlation analysis between the monitoring data, surface friction characteristics and tribofilm formation. Increasing tool wear tests were monitored to find early runnability warning.

    Results shows Acoustic emissions indication potential when the finishing process has achieved the intended friction reduction, tribofilm deposition as well as runnability issues identification.

  • 87.
    Suarez, Aldara Naveira
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Pasaribu, Rihard
    SKF Engineering & Research Center, Nieuwegein.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    The influence of base oil polarity on the tribological performance of zinc dialkyl dithiophospate additives2010In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 43, no 12, p. 2268-2278Article in journal (Refereed)
    Abstract [en]

    ZDDP blended in two base oils with different polarities were tested in mixed rolling-sliding conditions. The results showed significant differences in friction and wear when the additive is blended in the different oils. When ZDDP is blended in a non-polar base oil, the additive molecules have a better access to the steel surface, leading to higher adsorption rates than when ZDDP is blended in a polar oil, resulting in the formation of thicker ZDDP-derived reaction layers and influencing tribological performance. These results indicate the importance of base oil polarity on the ability of ZDDP to reach the surface and the influence on tribological performance.

  • 88.
    Söderfjäll, Markus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    A model for twin land oil control rings2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 95, p. 475-482Article in journal (Refereed)
    Abstract [en]

    A simulation model for predicting performance of a twin land oil control ring (TLOCR) in a heavy duty diesel engine (HDDE) has been developed. The simulation model takes into account the tribological interfaces of the TLOCR both against the cylinder liner and the piston ring groove. It also accounts for the elastic deformation of the ring cross section as well as the dynamics of the TLOCR. This work describes the model and discusses the challenges and compromises that had to be made. Included are also examples of the models capability to quantify design changes of the TLOCR.

  • 89.
    Söderfjäll, Markus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Component test for simulation of piston ring: Cylinder liner friction at realistic speeds2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 104, p. 57-63Article in journal (Refereed)
    Abstract [en]

    The piston ring cylinder liner contact is a large contributor to mechanical friction losses in internal combustion engines. It is therefore important to have methods and tools available for investigations of these frictional losses. This paper describes the design of a novel component test rig which is developed to be run at high speeds with unmodified production piston rings and cylinder liners from heavy duty diesel engines. A simplified floating liner method is used and the test equipment is developed to fill the gap in between a full floating liner engine and typical component bench test equipment. The functionality and repeatability of the test are investigated and an unexpected behaviour of the twin land oil control ring is found

  • 90.
    Söderfjäll, Markus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Herbst, Hubert M.
    Scania CV AB, Södertälje.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Influence on friction from piston ring design, cylinder liner roughness and lubricant properties2017In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 116, p. 272-284Article in journal (Refereed)
    Abstract [en]

    The piston rings are responsible for a large portion of the fuel consumption in heavy duty diesel engines. In this work a high speed component test rig for evaluation of piston ring friction is used. A number of different piston rings and cylinder liners are evaluated based on their friction performance. Shear thinning of typical multi grade oil is investigated by comparing it to single grade oil. Experimental simulation of higher speeds by decreasing the viscosity is evaluated. A method for indication of effects on oil consumption, without combustion, for different oil control rings is presented. Finally, a numerical simulation model for the oil control ring is validated by comparing the friction predicted with the model to the experimental results

  • 91.
    Tamayo, Juan Guillermo Zapata
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Björling, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Micropitting performance of Glycerol-based lubricants under rolling-sliding contact conditions2022In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 167, article id 107348Article in journal (Refereed)
    Abstract [en]

    There is a high demand for environmentally friendly lubricants in order to support a transition to sustainable transport and manufacturing since conventional mineral oils derived from fossil sources are inherently harmful for the environment. Glycerol aqueous solutions have the potential to be used as environmentally friendly base fluids, due to their high solubility in water, and non-toxicity. In this investigation a micropitting test rig (MPR), was used to study the friction, wear and micropitting behaviour of Glycerol-based lubricants in a rolling/sliding contact. Micropitting and wear profiles were analysed through optical profilometry, and the morphology and evolution of micropits were studied trough scanning electron microscopy (SEM). The results showed that the steel-steel contact lubricated with a Glycerol-water-glycol lubricant reduced mild-wear, promoting micro-pitting as a main failure mode at low sliding levels compared to a commercial fully formulated gear oil. It was also shown that friction was significantly lower for the Glycerol-water and Glycerol-water-glycol lubricants which is mainly attributed to an effect of a low pressure-viscosity coefficient.

  • 92.
    Tomala, A.
    et al.
    AC²T research GmbH - Austrian Center of Competence for Tribology, Viktor-Kaplan-Straße 2 D, 2700 Wiener Neustadt.
    Hernandez, Sinuhe
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ripoli, M. Rodriguez
    AC²T research GmbH - Austrian Center of Competence for Tribology, Viktor-Kaplan-Straße 2 D, 2700 Wiener Neustadt.
    Badisch, E.
    AC²T research GmbH - Austrian Center of Competence for Tribology, Viktor-Kaplan-Straße 2 D, 2700 Wiener Neustadt.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological performance of some solid lubricants for hot forming through laboratory simulative tests2014In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 74, p. 164-173Article in journal (Refereed)
    Abstract [en]

    Tribological research concerning sliding contacts at temperatures of 500–1000 °C has received limited attention. Industrial systems operating under high temperatures can be readily found in sheet metal forming processes. The control of friction during the tool-workpiece interaction and minimization of tool wear are both crucial in maintaining the products quality. The application of solid lubricants can be a possible approach in accomplishing these goals.The objective of this work is to investigate the reliability of combined model and component tests under solid lubricating conditions. The laboratory tests showed that both methodologies provide consistent results in exploring potential of the solid lubricants

  • 93.
    Tormos, Bernardo
    et al.
    CMT-Motores Térmicos, Universitat Politècnica de València, Avenida Naranjos S/N, 46022 Valencia, Spain.
    Ramíreza, Leonardo
    CMT-Motores Térmicos, Universitat Politècnica de València, Avenida Naranjos S/N, 46022 Valencia, Spain.
    Johansson, Jens
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Björling, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Fuel Consumption and Friction Benefits of Low Viscosity Engine Oils for Heavy Duty Applications2017In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 110, p. 23-34Article in journal (Refereed)
    Abstract [en]

    One of the most attractive ways to tackle vehicle engine's inefficiencies is the use of Low Viscosity Engine Oils (LVEO). Adopted some decades ago for their use in the Ligh Duty segment, LVEO are now reaching the Heavy Duty segment.

    In this study, a comparative fuel consumption test, where a LVEO performance is evaluated on an urban compressed natural gas buses fleet is portrayed. Then the friction performance of the same oils are studied on a Cameron-Plint tribometer, on an adapted twin disc tribometer to simulate journal bearing friction and on a Ball-on-Disc rig, using real engine parts in the former and the same set of engine oils used during the fleet test.

    Results show a fuel consumption reduction in the fleet test and corresponding friction reduction in the tribometers when LVEO are used.

  • 94.
    Torres, Hector
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. AC2T Research GmbH.
    Vuchkov, T.
    AC2T Research GmbH.
    Rodríguez Ripoll, Manel
    AC2T research GmbH.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological behaviour of MoS2-based self-lubricating laser cladding for use in high temperature applications2018In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 126, p. 153-165Article in journal (Refereed)
    Abstract [en]

    Many high temperature (HT) forming processes require the use of solid lubricants in order to control friction and reduce wear. In an attempt to eliminate the need for solid lubrication in high temperature sliding applications, nickel-based self-lubricating coatings with the addition of Ag and MoS2 were prepared by means of laser cladding on stainless steel substrates.

    The behaviour of the resulting laser claddings was thoroughly evaluated up to 600 °C, including the oxidation behaviour and reciprocating tribotesting using different counter body geometries (ball and flat pin). The self-lubricating coatings showed lower friction than the unmodified reference alloy at all tested temperatures, in addition to a significant microstructural stability after prolonged exposure at high temperatures. The addition of solid lubricants to the claddings was also found to be beneficial in terms of the counter body wear at HT, as no material loss could be measured for the bearing balls after testing at 600 °C against the self-lubricating claddings, despite the significant softening experienced by AISI 52100 bearing steel at HT.

  • 95.
    Ukonsaari, Jan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Wear and friction of synthetic esters in a boundary lubricated journal bearing2003In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 36, no 11, p. 821-826Article in journal (Refereed)
    Abstract [en]

    This study concerns the case of a slow intermittent motion, conformal contact, high load bronze journal bearing against a hardened steel shaft lubricated in an oil bath at a temperature about of 13 DGC. Three synthetic esters were used: one pure and two formulated ones. Worn surfaces were examined using SEM-EDS to determine the wear mechanism. The tested lubricants were examined using ICP-AES to identify the elements present. The results show the wear rate, friction and temperature in the subsurface of the journal bearing material. An initial bronze-steel contact develops into a copper-copper contact along the sliding distance. Wear element concentration in the oil and friction surfaces departs from the elementary concentration in the journal bearing bronze base material. The copper layer thickness depended on additives in the synthetic esters, load and wear rate.

  • 96.
    Vadivel, Hari
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Golchin, Arash
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological behaviour of carbon filled hybrid UHMWPE composites in water2018In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 124, p. 169-177Article in journal (Refereed)
    Abstract [en]

    In this study, newly developed hybrid composites with Ultra High Molecular Weight Polyethylene (UHMWPE) as base polymer and Graphene Oxide (GO), Nano Diamonds (ND) and Short Carbon Fibres (SCF) as fillers were manufactured. The tribological performance of these composites in a water lubricated sliding contact and the effect of inclusion of the fillers on the mechanical and thermal properties of the composites were investigated. The resulting hybrid composite formed by using the fillers and the base polymer displayed low friction coefficient and high wear resistance. Compared to unfilled UHMWPE, composite with all the fillers incorporated had 21% smaller friction coefficient and 15% less wear.

  • 97.
    Vakis, A.I.
    et al.
    Advanced Production Engineering, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen.
    Yastrebov, V.A.
    MINES ParisTech, PSL Research University, Centre des Matériaux, CNRS UMR 7633, BP 87, F 91003 Evry, France.
    Scheibert, J.
    Univ Lyon, Ecole Centrale de Lyon, ENISE, ENTPE, CNRS, Laboratoire de Tribologie et Dynamique des Systèmes LTDS, UMR 5513, F-69134, Ecully, France.
    Nicola, L.
    Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands; Department of Industrial Engineering, University of Padova, Via Venezia 1, 35015 Padua, Italy.
    Dini, D.
    Tribology Group, Department of Mechanical Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK.
    Minfray, C.
    Univ Lyon, Ecole Centrale de Lyon, ENISE, ENTPE, CNRS, Laboratoire de Tribologie et Dynamique des Systèmes LTDS, UMR 5513, F-69134, Ecully, France.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Paggi, M.
    IMT School for Advanced Studies Lucca, Multi-scale Analysis of Materials Research Unit, Piazza San Francesco 19, 55100 Lucca, Italy.
    Lee, S.
    Department of Mechanical Engineering, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
    Limbert, G.
    National Centre for Advanced Tribology at Southampton (nCATS), Bioengineering Science Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK;Biomechanics and Mechanobiology Laboratory, Biomedical Engineering Division, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, 7925, South Africa .
    Molinari, J.F.
    LSMS, ENAC, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.
    Anciaux, G.
    LSMS, ENAC, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland.
    Aghababaei, R.
    Department of Engineering, Aarhus University, Inge Lehmanns Gade 10, 8000 Aarhus C, Denmark.
    Echeverri Restrepo, S.
    SKF Engineering & Research Centre (ERC), SKF B.V., Nieuwegein, The Netherlands;Department of Physics, King's College London, Strand, London WC2R 2LS, England, UK .
    Papangelo, A.
    Hamburg University of Technology, Department of Mechanical Engineering, Am Schwarzenberg-Campus 1, 21073 Hamburg, Germany.
    Cammarata, A.
    Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Karlovo Namesti 13, 12135, Prague 2, Czech Republic.
    Nicolini, P.
    Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Karlovo Namesti 13, 12135, Prague 2, Czech Republic.
    Putignano, C.
    Politecnico di Bari, V. le Gentile 182, 70125 Bari, Italy.
    Carbone, G.
    Politecnico di Bari, V. le Gentile 182, 70125 Bari, Italy.
    Stupkiewicz, S.
    Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawinskiego 5B, 02-106 Warsaw, Poland.
    Lengiewicz, J.
    Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawinskiego 5B, 02-106 Warsaw, Poland.
    Costagliola, G.
    Department of Physics and Nanostructured Interfaces and Surfaces Centre, University of Torino, Via Pietro Giuria 1, 10125 Torino, Italy.
    Bosia, F.
    Department of Physics and Nanostructured Interfaces and Surfaces Centre, University of Torino, Via Pietro Giuria 1, 10125 Torino, Italy.
    Guarino, R.
    Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy.
    Pugno, N.M.
    Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy; Ket Lab, Edoardo Amaldi Foundation, Italian Space Agency, Via del Politecnico snc, 00133 Rome, Italy;School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1-4NS London, United Kingdom .
    Müser, M.H.
    Department of Materials Science and Engineering, Saarland University, 66123 Saarbrücken, Germany.
    Ciavarella, M.
    Politecnico di Bari, V. le Gentile 182, 70125 Bari, Italy.
    Modeling and simulation in tribology across scales: An overview2018In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 125, p. 169-199Article in journal (Refereed)
    Abstract [en]

    This review summarizes recent advances in the area of tribology based on the outcome of a Lorentz Center workshop surveying various physical, chemical and mechanical phenomena across scales. Among the main themes discussed were those of rough surface representations, the breakdown of continuum theories at the nano- and micro-scales, as well as multiscale and multiphysics aspects for analytical and computational models relevant to applications spanning a variety of sectors, from automotive to biotribology and nanotechnology. Significant effort is still required to account for complementary nonlinear effects of plasticity, adhesion, friction, wear, lubrication and surface chemistry in tribological models. For each topic, we propose some research directions.

  • 98.
    Vrček, Aleks
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hultqvist, Tobias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Baubet, Yannick
    SKF, Nieuwegein.
    Björling, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Micro-pitting and wear assessment of engine oils operating under boundary lubrication conditions2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 129, p. 338-346Article in journal (Refereed)
    Abstract [en]

    Current state-of-the-art engine oils tend to enhance micro-pitting damage in rolling contacts under certain operating conditions. ZDDP anti-wear additive was shown to promote such behavior. However, in order to optimize an engine oil formulation for rolling contacts, further studies are needed to assess engine oils in terms of micro-pitting and wear damage. This investigation studies the micro-pitting and wear performance of a number of engine oils for rolling contacts in a ball-on-disc configuration under conditions prevalent in crankshaft roller bearing applications. Based on the results it was concluded that an engine oil containing higher blend of PAO base oil compared to the oil mixture of Group III and PAO has a lower tendency towards micro-pitting and wear.

  • 99.
    Vrček, Aleks
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hultqvist, Tobias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Baubet, Yannick
    SKF Research and Technology Development, Nieuwegein, Netherlands.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Micro-pitting Damage of Bearing Steel Surfaces under Mixed Lubrication Conditions: Effects of Roughness, Hardness and ZDDP Additive2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 138, p. 239-249Article in journal (Refereed)
    Abstract [en]

    Micro-pitting presents a failure of the rolling/sliding contact metal asperities operating under boundary/mixed lubrication conditions. The studies have shown that micro-pitting failure competes with mild wear and that lubricant additives can have either detrimental or beneficial effects on micro-pitting evolution. This article describes a methodology to investigate micro-pitting damage on bearing steels using a twin-disc machine to better represent mechanical components, i.e. bearings, crankshafts, etc. In addition, effects of roughness, hardness and the ZDDP additive are presented and discussed. A sufficient hardness difference can completely eliminate micro-pitting damage mode. Furthermore, the presence of ZDDP anti-wear additive in fully formulated engine oil was shown to protect rougher surfaces and promote wear on smoother surfaces, thus completely eliminating the micro-pitting damage mode.

  • 100.
    Vuorinen, Esa
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ojala, N.
    Tampere University of Technology, Department of Materials Science, Tampere Wear Center.
    Heino, V.
    Tampere University of Technology, Department of Materials Science, Tampere Wear Center.
    Rau, Christoph
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gahm, Christian
    LKAB, Produktion Teknik, SE-98381 Malmberget.
    Erosive and abrasive wear performance of carbide free bainitic steels: comparison of field and laboratory experiments2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 98, p. 108-115Article in journal (Refereed)
    Abstract [en]

    Carbide free bainitic (CFB) steels have been tested in two heat treated conditions and compared with currently used quenched and tempered (QT) steel in an industrial mining application subjected to erosive-abrasive wear. A conventional sliding abrasion and a new application oriented high-stress erosion wear tests were performed in laboratory. The results of the erosion and the field tests were compared. The microstructural changes were investigated by optical and scanning electron microscopy. The hardness and hardness profiles of the steels were measured. The results showed that in the laboratory tests, the abrasion and erosion wear rates of the CFB steels were 35 and 45% lower respectively in comparison to the QT steel. In the field test, the mass losses of the CFB steels were about 80% lower in comparison with the QT steel. The improved wear resistance of the CFB steel can be explained by its higher hardness and higher work hardening. The erosion wear test was able to simulate the work hardening effect and the wear mechanisms observed in the field test samples.

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