Full-scale testing of low adhesion effects with small amounts of water in the wheel/rail interface
Publication date: Available online 16 August 2019Source: Tribology InternationalAuthor(s): L.E. Buckley-Johnstone, G. Trummer, P. Voltr, K. Six, R. LewisAbstractLow adhesion in the wheel/rail contact can be caused by small amounts of water combining with iron oxides. This happens in light rain or at dew point. In small-scale tests, ultra-low adhesion (≤0.05) has not been maintained. The aim here was to see if the mechanism could be realized at a larger scale. Sustained ultra-low adhesion was achieved when water was applied constantly to the wheel/rail contact at a rate of 25μL/s. In these conditions wear debris and o...
Source: Tribology International - August 18, 2019 Category: Materials Science Source Type: research

Study of the mechanism of friction on functionally active tribological Polyvinyl Chloride (PVC) – Aggregate composite surfaces
Publication date: Available online 15 August 2019Source: Tribology InternationalAuthor(s): Konstantinos Giannoukos, Konstantinos SalonitisAbstractPolyvinyl Chloride based surfaces present a relatively low coefficient of friction (COF), but this can be improved if silicon carbide is dispersed on the surface. In the present paper an experimental investigation is presented for assessing the efficiency of the use of SiC aggregates for this purpose. FTIR and DSC methods were used for assessing the curing of the composite surfaces. Optical microscopy was used for assessing the geometrical characteristics of the SiC aggregates. T...
Source: Tribology International - August 16, 2019 Category: Materials Science Source Type: research

Environmental atmosphere effect on lubrication performance of gallium-based liquid metal
Publication date: Available online 14 August 2019Source: Tribology InternationalAuthor(s): Pengpeng Bai, Shaowei Li, Wenpeng Jia, Liran Ma, Yonggang Meng, Yu TianAbstractThe friction and wear properties of Gallium-based liquid metal (GBLM)-lubricated bearing steel friction pairs were investigated with a rotating ball-on-disk contact test under nitrogen, air, and oxygen atmospheres. The coefficient of friction (COF) and wear rate of steel lubricated with GBLM were lower in aerobic environments than those in anaerobic environments. In air, the wear rates and COFs increased with higher humidities, and COFs decreased in the in...
Source: Tribology International - August 16, 2019 Category: Materials Science Source Type: research

High temperature tribological behaviors and wear mechanisms of NiAl–NbC–Ag composites formed by in-situ decomposition of AgNbO3
Publication date: Available online 13 August 2019Source: Tribology InternationalAuthor(s): Xiaochun Feng, Cheng Lu, Junhong Jia, Jiali Xue, Qihua Wang, Yuan Sun, Wenzhen Wang, Gewen YiAbstractNiAl–NbC–Ag composites were successfully prepared by vacuum-hot-pressing sintering with directly addition of AgNbO3 powders, where AgNbO3 were synthesized using a solid state reaction method. The tribological behaviors of composites were evaluated from 25 °C to 800 °C. The consequences reveal AgNbO3 are completely decomposed during sintering process and in-situ formed NiAl–NbC–Ag composites, which h...
Source: Tribology International - August 15, 2019 Category: Materials Science Source Type: research

Effect of load on the friction and wear characteristics of Si3N4-hBN ceramic composites sliding against PEEK in artificial seawater
Publication date: Available online 13 August 2019Source: Tribology InternationalAuthor(s): Wei Chen, Zhaoxun Wang, Xing Liu, Junhong Jia, Yue HuaAbstractIn this paper, the tribological characteristics of Si3N4-hBN ceramic composites sliding against poly-ether-ether-ketone in artificial seawater were investigated, and the normal load was varied from 10 N to 30 N in the step of 10 N to investigate the effect. It can be found that the tribological performance of sliding pair improved with the increasing load. This result was attributed to the complex factor about the polymer characteristics, the seawater environment and...
Source: Tribology International - August 15, 2019 Category: Materials Science Source Type: research

Effect of the progressive tool wear on surface topography and chip formation in micro-milling of Ti–6Al–4V using Ti(C7N3)-based cermet micro-mill
Publication date: Available online 11 August 2019Source: Tribology InternationalAuthor(s): Yishun Wang, Bin Zou, Juncheng Wang, You Wu, Chuanzhen HuangAbstractTitanium alloy is extremely difficult to machine due to the rapid tool wear. The influence of tool wear on surface topography and chip formation, during micro-milling of Ti–6Al–4V, using Ti(C7N3)-based cermet micro-mill is investigated. The non-uniform surface quality was generated by alternative material removal mechanisms, at the cross-section of micro-slot. Metal debris and plastic side flow were more severe as the tool wear progressed, while the impro...
Source: Tribology International - August 12, 2019 Category: Materials Science Source Type: research

Modelling for water-based liquid lubrication with ultra-low friction coefficient in rough surface point contact
Publication date: Available online 10 August 2019Source: Tribology InternationalAuthor(s): Yanfei Fang, Liran Ma, Jianbin LuoAbstractIn this paper, a composite model of average flow Reynolds equation with considering electrical double layer (EDL) effect in roughness surface is proposed to analysis aqueous solution lubrication performance. The numerical simulations are conducted to explain the phenomena of water-based lubrication with ultra-low friction coefficient. The results have showed that: The EDL hydrodynamic and asperity contact will work together to balance the out applied load. The EDL effect has greatly benefited...
Source: Tribology International - August 12, 2019 Category: Materials Science Source Type: research

Fretting fatigue lifetime estimation using a cyclic cohesive zone model
Publication date: Available online 9 August 2019Source: Tribology InternationalAuthor(s): K. Pereira, M. Abdel WahabAbstractOver the past decades, many numerical procedures aiming to predict the life of components subjected to fretting fatigue have been developed. Most procedures combine estimates of crack initiation and propagation lives in order to obtain total lifetime. Nevertheless, crack initiation life estimates are generally not easy to define. An alternative is to consider the failure in a cycle-by-cycle analysis using cyclic cohesive zone model (CCZM), accounting for loading and unloading damage accumulation at cr...
Source: Tribology International - August 11, 2019 Category: Materials Science Source Type: research

Film thickness build-up in zero entrainment velocity wide point contacts
Publication date: Available online 7 August 2019Source: Tribology InternationalAuthor(s): Bilel Meziane, Philippe Vergne, Nicolas Devaux, Lionel Lafarge, Guillermo E. Morales-Espejel, Nicolas FillotAbstractIn this work, elastohydrodynamic wide point contacts are studied under Zero Entrainment Velocity (ZEV) conditions. Contrary to classical rolling-sliding contacts, no hydrodynamic lift (oil wedge effect) is expected in stationary isothermal ZEV contacts. However, both experiments and numerical simulations taking into account temperature gradients in the thickness of the lubricant show the occurrence of a full-film lubrica...
Source: Tribology International - August 8, 2019 Category: Materials Science Source Type: research

The effect of lubricant additives on the tribological performance of oil and gas drilling applications up to 200 °C
Publication date: Available online 6 August 2019Source: Tribology InternationalAuthor(s): Pixiang Lan, Larry L. Iaccino, Xiaoying Bao, Andreas A. PolycarpouAbstractAdding lubricant additives is a predictable method to decrease the frictional resistance in oil and gas drilling applications. In this work, tribological studies were carried out for drilling fluid with/without lubricant additives at different temperatures up to 200 °C and environmental pressure of 3.45 MPa. In pure fluid, additive A exhibited higher load capacity, compared to additive B at 200 °C. In drilling fluid, at 75 °C, all additives d...
Source: Tribology International - August 8, 2019 Category: Materials Science Source Type: research

Adaptive indirect neural network model for roughness in honing processes
Publication date: Available online 3 August 2019Source: Tribology InternationalAuthor(s): Irene Buj-Corral, Maurici Sivatte-Adroer, Xavier Llanas-ParraAbstractHoning processes provide a crosshatch pattern that allows oil flow, for example in combustion engine cylinders. This paper provides an adaptive neural network model for predicting roughness as a function of process parameters. Input variables are three parameters from the Abbott-Firestone curve, Rk, Rpk and Rvk. Output parameters are grain size, density of abrasive, pressure, linear speed and tangential speed. The model consists of applying a direct and an indirect m...
Source: Tribology International - August 5, 2019 Category: Materials Science Source Type: research

Thermo-elastohydrodynamic mixed-lubrication model for reciprocating rod seals
Publication date: Available online 4 August 2019Source: Tribology InternationalAuthor(s): Chong Xiang, Fei Guo, Xiaohong Jia, Yuming Wang, Xing HuangAbstractA thermo-elastohydrodynamic lubrication model of a typical VL combined reciprocating rod seal is established to analyze thermal-viscous effects on the reciprocating rod sealing system. Both the inverse and elastohydrodynamic lubrication theories are interactively applied to calculate the pressure and thickness of the lubrication film. The influence coefficient method is used to couple the fluid mechanics, macroscopic solid mechanics, and microscopic contact mechanics. ...
Source: Tribology International - August 5, 2019 Category: Materials Science Source Type: research

Improvement of tribological behavior of H-13 steel by optimizing the cryogenic-treatment process using evolutionary algorithms
Publication date: Available online 5 August 2019Source: Tribology InternationalAuthor(s): Sanjeev Katoch, Rakesh Sehgal, Vishal Singh, Munish Kumar Gupta, Mozammel Mia, Catalin Iulian PruncuAbstractThe effect of soaking temperature and duration of cryogenic treatment cycles were investigated for the hot die steel AISI-H13 to improve its wear resistance. The amount of wear, average friction coefficient, and maximum local contact temperature were investigated against the AISI D3 cold work tool steel (hardened and tempered) used as counter-surface for five conditions – varying the loading and sliding speed. Sliding para...
Source: Tribology International - August 5, 2019 Category: Materials Science Source Type: research

Measurement of strain evolution in overloaded roller bearings using energy dispersive X-ray diffraction
This study presents a novel technique capable of measuring subsurface strain evolution in a rotating roller bearing, using energy dispersive X-ray diffraction. A pre-overloaded bearing was tested dynamically and consequently failed prematurely, supporting the hypothesis that overloads accelerate bearing failure. Throughout the test, an increase in compressive radial strain was observed, indicative of material softening, generally associated with the unstable stage of rolling contact fatigue, which occurs prior to definitive bearing failure.Graphical abstract (Source: Tribology International)
Source: Tribology International - August 3, 2019 Category: Materials Science Source Type: research

The microstructure and properties of bronze matrix composites with surface-modified graphite by titanium carbide adhesion
Publication date: Available online 2 August 2019Source: Tribology InternationalAuthor(s): Jiaming Pan, Jinwei Yin, Yongfeng Xia, Dongxu Yao, Hanqin Liang, Kaihui Zuo, Yuping ZengAbstractBronze matrix composites were prepared by powder metallurgy method using graphite as the lubricant, titanium carbide (TiC) attached to the surface of graphite was introduced by Self-propagating High-temperature Synthesis (SHS) in order to improve the bronze/graphite interfacial bonding. As a result, the composites became denser, and the mechanical properties were enhanced. Moreover, the experiments of friction indicated that the composites ...
Source: Tribology International - August 2, 2019 Category: Materials Science Source Type: research

Competition between surface and subsurface rolling contact fatigue failures of nitrided parts: A Dang Van approach
This study focuses on the prediction of the location of crack initiation for gas-nitrided steels subjected to rolling contact fatigue taking into account the material property gradients induced by the nitriding process. Several approaches based on the Dang Van criterion are compared to experimental data to find the most reliable prediction model. (Source: Tribology International)
Source: Tribology International - August 2, 2019 Category: Materials Science Source Type: research

Morphological and structural features affecting the friction properties of carbon materials for brake pads
Publication date: Available online 1 August 2019Source: Tribology InternationalAuthor(s): Maria Giulia Faga, Enrico Casamassa, Valentina Iodice, Agusti Sin, Giovanna GautierAbstractSix carbon materials, the widespread solid lubricant used in several applications, were selected for this study. The morphological and structural features were investigated with the purpose to understand how materials intrinsic properties affect the friction behaviour, using a pin-on-disc test applied to carbon powders against steel at different values of load and speed. The influence of test variables and material properties was studied using a...
Source: Tribology International - August 2, 2019 Category: Materials Science Source Type: research

One step synthesis of ZnO nanoparticles from ZDDP and its tribological properties in steel-aluminum contacts
Publication date: Available online 1 August 2019Source: Tribology InternationalAuthor(s): Yuanyuan Zhang, Yujuan Zhang, Shengmao Zhang, Guangbin Yang, Chuanping Gao, Changhua Zhou, Chunli Zhang, Pingyu ZhangAbstractIn order to overcome the poor lubricity of zinc dialkyldithiophosphate (ZDDP) in aluminum contacts, ZnO nanoparticles (ZODDP) modified with dialkyldithiophosphoric acid were prepared through one step process from ZDDP. Compared with ZDDP the sulfur and phosphorus contents of ZODDP decreased by 77.9%~82.8% and 77.3~80.7%. respectively. The tribological properties of ZODDP as the additives of diisooctyl sebaca...
Source: Tribology International - August 2, 2019 Category: Materials Science Source Type: research

A study of inlet temperature models of a large size tilting thrust bearing comparison between theory and experiment
Publication date: Available online 29 July 2019Source: Tribology InternationalAuthor(s): Shifu Yang, Chao Li, Mulong Jiang, Shiyuan PeiAbstractIn the tilting pad of a thrust bearing, the oil film temperature is very sensitive to the inlet temperature boundary condition. Three methods, including the supply oil temperature method, the heat boundary layer method, and the hot oil carry-over method, were discussed and analyzed. In order to improve the accuracy of calculation results, a coupled computing model was established and calculated. A large bearing 1:1 experimental bench was designed to verify the rule of influence of t...
Source: Tribology International - July 30, 2019 Category: Materials Science Source Type: research

Non-linear model order reduction for elastohydrodynamic lubrication simulations of polymer seals
Publication date: Available online 29 July 2019Source: Tribology InternationalAuthor(s): F. Ischinger, D. Bartel, M. Brunk, S. SolovyevAbstractIn the field of elastohydrodynamic lubrication (EHL) simulations, the importance of considering non-linearities in the structure increases constantly. In most cases, the finite element method is used to discretize the non-linear continuum equations. Apart from this, model order reduction techniques are used in EHL simulations to decrease the number of unknowns and the computational time. However, the reduction methods typically used are limited to linear problems.The aim of this pap...
Source: Tribology International - July 30, 2019 Category: Materials Science Source Type: research

Enhancing interfacial and tribological properties of self-lubricating liner composites via Layer-by-Layer self-assembly MgAl-LDH/PAMPA multilayers film on fibers surface
Publication date: Available online 27 July 2019Source: Tribology InternationalAuthor(s): Mingming Yang, Zhaozhu Zhang, Liangfei Wu, Peilong Li, Wei Jiang, Xuehu MenAbstractInterfacial properties between reinforcement and resin matrix have significantly influence on the tribological and mechanical behaviors of self-lubricating liner composites. Introducing nanoscale fillers onto fibers surface can significantly enhance the surface energy and roughness, which contributed to improve the adhesion strength. In this work, MgAl-LDH/PAMPA multilayers films were loaded onto Nomex and PTFE fibers surface by a simple and high efficie...
Source: Tribology International - July 29, 2019 Category: Materials Science Source Type: research

Insight into the lubricating mechanism for alkylimidazolium phosphate ionic liquids with different alkyl chain length
Publication date: Available online 26 July 2019Source: Tribology InternationalAuthor(s): Guowei Huang, Shukai Fan, Zhaowen Ba, Meirong Cai, Dan QiaoAbstractThree kinds of alkylimidazolium phosphate ionic liquids (ILs) with different alkyl-chain length of cations are synthesized and their friction-reducing and antiwear properties for steel/steel sliding pairs are enhanced with the increasing of the alkyl-chain length. The lubricating mechanism can be attributed to two aspects: on the one hand, the contact electrical resistance (ECR), corrosion, electrochemical test results reveal that ILs with longer alkyl-chains exhibit be...
Source: Tribology International - July 27, 2019 Category: Materials Science Source Type: research

Conjugate approach for hypoid gears frictional loss comparison between different roughness patterns under mixed elastohydrodynamic lubrication regime
Publication date: Available online 26 July 2019Source: Tribology InternationalAuthor(s): Dequan Huang, Zhonghou Wang, Gang Li, Weidong ZhuAbstractThis paper compares the frictional loss of hypoid gears between three different tooth surface roughness patterns under the mixed elastohydrodynamic lubrication regime, namely the striated, the isotropic and the less roughed. Conjugate approach contact model for such purpose is proposed, which aids in determination of the parameters input for the lubrication model and construction of wanted tooth surface roughness patterns, by integrating the digital tooth surface technique, the c...
Source: Tribology International - July 27, 2019 Category: Materials Science Source Type: research

Third-body and crack behavior in white etching layer induced by sliding–rolling friction
Publication date: Available online 23 July 2019Source: Tribology InternationalAuthor(s): Yan Zhou, Ji-liang Mo, Zhen-bing Cai, Chang-guang Deng, Jin-fang Peng, Min-hao ZhuAbstractThe tribologically transformed structure of the white etching layer (WEL) always appears with some cracks accompanying microstructural evolution under friction. This work investigated crack behavior with the existence of WEL on pearlitic steel after rolling-sliding friction tests. The WEL microstructure was characterized using scanning electron microscopy, nano-indentation, focused ion beam, and transmission electron microscopy. According optical ...
Source: Tribology International - July 24, 2019 Category: Materials Science Source Type: research

Mixed-lubrication analysis of planetary roller screw
Publication date: Available online 24 July 2019Source: Tribology InternationalAuthor(s): Zhijie Xie, Qihe Xue, Jiqiang Wu, Le Gu, Liqin Wang, Baoyu SongAbstractThe mixed-lubrication model of the planetary roller screw is proposed considering contact load, contact geometry of thread, surface roughness and transient effects. The influences of rotational speed of the screw, axial load and surface roughness on lubrication are discussed. Increasing rotational speed has a significant effect on the lubrication of contact areas. As the speed increases, the film thickness increases while the friction coefficient and contact-area ra...
Source: Tribology International - July 24, 2019 Category: Materials Science Source Type: research

Tribological behaviour of surfaces with stepped wettability under limited lubricant supply
Publication date: Available online 21 July 2019Source: Tribology InternationalAuthor(s): C.L. Liu, F. Guo, P.L. Wong, X.M. LiAbstractUsing less lubricant is currently a trend in tribology design to address fuel economy and environment concerns. The present study was conducted to identify how an oleophilic lubrication track bounded by oleophobic areas achieves efficient lubrication under limited lubricant supply (LLS) conditions. Findings showed that the stepped wettability formed at the border of the oleophilic track can reduce the coefficient of friction and wear for steel ball-on-steel plate contact in a mixed lubricatio...
Source: Tribology International - July 23, 2019 Category: Materials Science Source Type: research

Numerical simulation of mixed lubrication considering surface forces
Publication date: Available online 18 July 2019Source: Tribology InternationalAuthor(s): Shuowen Zhang, Chenhui Zhang, Yuanzhong Hu, Liran MaAbstractMixed lubrication describes a lubrication regime where elastohydrodynamic lubrication and asperity contact coexist. Surface spacing is expected to be small during the interaction between nano-scale smooth surfaces. When alkali metal salt solution is applied as lubricant, short-range surface forces are incorporated into an existing model to simulate mixed lubricated non-conformal sliding contact. The new model is examined in a wide range of sliding velocities to demonstrate the...
Source: Tribology International - July 20, 2019 Category: Materials Science Source Type: research

Hydrodynamic lubrication analysis of two-dimensional section between piston skirt and textured cylinder wall considering slip boundary conditions
Publication date: Available online 18 July 2019Source: Tribology InternationalAuthor(s): Chao Guo, Qinghua Song, Zhanqiang Liu, Long ChenAbstractSurface micro-texturing with slip boundary has attracted extensive attention. To accurately investigate the coupling influences of slip and micro-texturing on piston skirt lubrication performance, a comprehensive method called Reynolds-Stokes Galerkin finite element method (R-SGFEM) is proposed. Modified Reynolds equation is employed to calculate slip velocity by Navier slip model, and lubrication flow is solved by Stokes systems using the Galerkin finite element method. This meth...
Source: Tribology International - July 20, 2019 Category: Materials Science Source Type: research

Wear behavior of CADI obtained at different austenitizing temperatures
Publication date: Available online 19 July 2019Source: Tribology InternationalAuthor(s): Yang Penghui, Fu Hanguang, Zhao Xiangwei, Lin Jian, Lei YongpingAbstractThe microstructure, mechanical properties and wear resistance of carbidic austempered ductile iron (CADI) obtained at different austenitizing temperatures were investigated. The dry sliding wear failure mechanism in block-on-ring tester and erosive wear failure mechanism of CADI in the slurry of pH = 4, pH = 10 were analyzed. The results show that with the increase of austenitizing temperature, the hardness and tensile strength of CADI first increase and th...
Source: Tribology International - July 20, 2019 Category: Materials Science Source Type: research

An extended Elrod-Adams model to account for backpressure and blow-by inception
Publication date: Available online 17 July 2019Source: Tribology InternationalAuthor(s): Alfredo Jaramillo, Gustavo C. BuscagliaAbstractThe Piston-Ring-Liner system is the main tribological component of internal combustion engines. Hydrodynamic models are customarily used to numerically assess the performance of different ring designs and liner surface treatments. However, available models do not properly incorporate the backpressure boundary condition, which corresponds to the combustion chamber pressure and is quite significant. A new model is proposed here that imposes the combustion-chamber pressure in a mass-conservin...
Source: Tribology International - July 18, 2019 Category: Materials Science Source Type: research

Microstructural changes on railway track surfaces caused by electrical leakage between wheel and rail
Publication date: Available online 17 July 2019Source: Tribology InternationalAuthor(s): Ali Al-Juboori, Hongtao Zhu, David Wexler, Huijun Li, Cheng Lu, Azdiar A. Gazder, John McLeod, Shamal Pannila, Jonathan BarnesAbstractWhite etching layers (WELs) are one of the main causes of rail surface degradation, which play the important roles on the contact mechanism and tribology behaviours at wheel and rail interface. An electrical arcing due to current leakage was investigated as a new potential source of thermally induced WELs. Both electrical arcing induced WELs and ex-service WELs comprise similar microstructures, consistin...
Source: Tribology International - July 18, 2019 Category: Materials Science Source Type: research

Microstructure and tribological properties of ZrO2(Y2O3)–Al2O3-graphite composite ceramic fabricated by milling with graphite balls
In this study, ZrO2(Y2O3)–Al2O3-graphite composite powder was prepared by a mechanical milling method and a direct powder doping milling method, and sintered in a microwave. Microstructure and tribological properties of the composites were investigated. The results showed that uniformly dispersed fine graphite flakes were obtained using the mechanical milling method. ZrC phase was generated in the composite ceramics. The tribological properties of ZrO2(Y2O3)–Al2O3- graphite composites prepared by the mechanical milling method were better than those of ZrO2(Y2O3)–Al2O3-graphite composites prepared by the d...
Source: Tribology International - July 18, 2019 Category: Materials Science Source Type: research

Experimental investigations of the internal friction in automotive bush chain drive systems
Publication date: Available online 16 July 2019Source: Tribology InternationalAuthor(s): Robert Tandler, Niels Bohn, Ulrich Gabbert, Elmar WoschkeAbstractIn this paper the measurements of the internal chain friction of a bush chain for various engine parameters are studied with a focus on petrol engines and the influence of engine oil.Due to the combustion of a petrol engine, the engine oil contains numerous particles and chemical bonds that have a significant impact on the internal chain friction.In order to measure the internal chain friction an experimental set-up has been developed excluding the influence of guide rail...
Source: Tribology International - July 18, 2019 Category: Materials Science Source Type: research

Dynamic behaviour of a bolted joint subjected to torsional excitation
Publication date: Available online 16 July 2019Source: Tribology InternationalAuthor(s): Jianhua Liu, Huajiang Ouyang, Zhiqiang Feng, Zhenbing Cai, Jiliang Mo, Jinfang Peng, Minhao ZhuAbstractThis paper presents results of experimental and theoretical studies on the dynamics of a bolted joint under torsional excitation. Hysteresis curves of the resultant torque versus the applied angle of twist are obtained from the experimental results. These experiments have shown relative slippages between the clamped parts and between the contact threads. Based on the experimental results, the coefficients of friction between the conta...
Source: Tribology International - July 18, 2019 Category: Materials Science Source Type: research

Effect of temperature on friction and galling behavior of 7075 aluminum alloy sheet based on ball-on-plate sliding test
Publication date: Available online 16 July 2019Source: Tribology InternationalAuthor(s): Jue Lu, Yanli Song, Lin Hua, Pu Zhou, Guangju XieAbstractIn this work, the friction and galling properties of 7075 aluminum alloy sheet at different temperatures from ambient to 400 °C have been investigated by performing linear unlubricated reciprocating sliding tests on a ball-on-plate tribometer. It was found that a compacted layer could be formed on the worn surface and its effect on the friction behavior of the alloy was determined. Thereafter, coupled with dissolution-precipitation of the hard phase, a friction evolution mo...
Source: Tribology International - July 18, 2019 Category: Materials Science Source Type: research

A thermohydrodynamic approach for single-film and double-film floating disk fixed thrust bearings verified with experiment
Publication date: Available online 15 July 2019Source: Tribology InternationalAuthor(s): Saeid Dousti, Paul AllaireAbstractA comprehensive thermohydrodynamic model of single-film and double-film floating disk thrust bearings is presented. Reynolds and energy equations are solved and a modified groove mixing model is used to predict the oil leading edge temperature. A multi-step search algorithm is used to find floating disk rotational speed, and the two film thicknesses. Results are validated with experimental data. It is shown that the floating disk rotates with 30%–50% of the runner rotational speed. The turbine si...
Source: Tribology International - July 17, 2019 Category: Materials Science Source Type: research

Temperature/shear-induced interface reconstruction of hot rolled carbon steel lubricated by polyphosphate composite lubricants
Publication date: Available online 15 July 2019Source: Tribology InternationalAuthor(s): Shanhong Wan, Huynh H. Nguyen, Sang T. Pham, Anh Kiet Tieu, Hongtao Zhu, Thi Dinh Ta, Qiang ZhuAbstractThe present work aims to investigate temperature/shear-induced oxide reconstruction at the hot rolled steel interface, where sodium/potassium polyphosphates blended with different oxide nanoparticles were applied as the lubricant to control friction and manage oxidation. The lubrication of alkaline polyphosphate reduces the rolling force by up to 15% and prevents oxidation significantly. The undesired oxide scale can be transformed in...
Source: Tribology International - July 17, 2019 Category: Materials Science Source Type: research

Three-dimensional mixed lubrication analysis of spur gears with machined roughness
In this study, by considering the three-dimensional (3D) machined roughness, an integrated model with the analysis of mixed lubrication state and dynamic-meshing performance for the spur gear is developed. The model is verified by comparing its results with the predictions using the typical line-contact EHL formulas. The machined roughness apparently affects the local 3D distributions of the film pressure and thickness. The shaved surfaces have the minimum film thickness ratio and the worst lubrication state, while the polished surfaces can improve the lubrication performance of the timing gear pairs greatly. Under the con...
Source: Tribology International - July 17, 2019 Category: Materials Science Source Type: research

Formation of the third bodies of steel sliding against brass under lubricated conditions
Publication date: December 2019Source: Tribology International, Volume 140Author(s): Lin Liu, Yuanyuan Sheng, Ming Liu, Martin Dienwiebel, Zhichen Zhang, Davoud DastanAbstractThis work investigates the formation mechanism of the third bodies for brass under lubricated conditions. A tribometer based on on-line and radio-nuclide technique (RNT) techniques is used to perform the sliding experiment of brass versus steel. The microstructure, micro-hardness and chemical composition of the third bodies are analyzed by mean of the scanning electron microscope (SEM), focused ion beam microscope (FIB), transmission electron microsco...
Source: Tribology International - July 17, 2019 Category: Materials Science Source Type: research

Evaluation of viscoelastic characteristics of PTFE-Based materials
Publication date: Available online 12 July 2019Source: Tribology InternationalAuthor(s): Bo Tan, Lyndon Scott StephensAbstractPTFE-based materials are widely used in areas of tribology, particularly in seal and bearing applications because of their outstanding self-lubricating properties. This paper concentrates on the viscoelastic response of PTFE-based materials. Using a dynamic mechanical analyzer (DMA), the storage modulus, loss modulus and tan δ, are measured and discussed in the frequency domain. The relaxation modulus and creep compliances are also measured and studied in the time domain. Finally, the materi...
Source: Tribology International - July 14, 2019 Category: Materials Science Source Type: research

A multiphase computational study of oil distribution inside roller bearings with under-race lubrication
Publication date: Available online 11 July 2019Source: Tribology InternationalAuthor(s): Wenjun Gao, Daniel Nelias, Kun Li, Zhenxia Liu, Yaguo LyuAbstractOil-phase distribution inside roller bearings with under-race lubrication is a key element for bearing lubricating and cooling, and it determines the bearing's hydraulic loss, which may represent up to 50% of total power dissipated. The CLSVOF method for multiphase flow is conducted to track oil/air two-phase flow inside roller bearing with under-race lubrication, and quantify the influence of various factors, particularly rotating speeds of bearing components. The result...
Source: Tribology International - July 12, 2019 Category: Materials Science Source Type: research

On the oil-gas-solid mixed bearing between compression ring and cylinder liner under starved lubrication and high boundary pressures
In this study, the oil-gas-solid mixed bearing characteristics and tribological properties of the top ring under starved lubrication are analyzed. It is found that the high boundary pressure has a significant effect and it can even compare with hydrodynamic lubrication and asperity contact near FTDCs. Besides, the influence of different textures is also investigated. It is found that textures are not always positive for improving the tribological performance of the piston ring-cylinder liner (PRCL) system. (Source: Tribology International)
Source: Tribology International - July 12, 2019 Category: Materials Science Source Type: research

Dynamic response of spiral groove liquid film seal to impact conditions
Publication date: Available online 10 July 2019Source: Tribology InternationalAuthor(s): Yongfan Li, Muming Hao, Xinhui Sun, Zhentao Li, Yunlei Wang, Lushuai Xu, Hengchao CaoAbstractThe dynamic response of the spiral groove liquid film seal to three types of impact are studied by developing a three-DOF dynamic model which takes average flow model, cavitation effect, squeeze effect and face contact into account. A Gaussian pulse function is first applied to simulate the impact to the seal. Results indicate that the seal can maintain hydrodynamic lubrication regime to avoid significant face contact regardless of the impact t...
Source: Tribology International - July 11, 2019 Category: Materials Science Source Type: research

Effects of rotor surface texture on rotary vane actuator end sealing performance
Publication date: Available online 10 July 2019Source: Tribology InternationalAuthor(s): Teng Hu, Liangxi Xie, Jingrong LiuAbstractThe dynamic pressure oil film is difficult to form between the end seal ring and the rotor during the hydraulic rotary vane actuator (RVA) operates, which results in the sealing surfaces sustain severe friction and wear. Thus, a series of circular micro-dimples was processed on the rotor surface using laser surface texturing technology to reduce these. The mathematical model of the end seal was established based on the fluid dynamic lubrication equation. In the meanwhile, the friction torque an...
Source: Tribology International - July 11, 2019 Category: Materials Science Source Type: research

Fluorinated graphene oxide nanosheet: A highly efficient water-based lubricated additive
Publication date: Available online 10 July 2019Source: Tribology InternationalAuthor(s): Chunying Min, Zengbao He, Haojie Song, Hongyu Liang, Dengdeng Liu, Changkun Dong, Wei JiaAbstractFluorinated graphene (FG) cannot be applied under aqueous environments due to its high hydrophobicity related to fluorine on FG nanosheet, so how to achieve the hydrophilic FG is a challenge. The novel water lubricant that manifests outstanding tribological properties were obtained using fluorinated graphene oxide (FGO) as additive which was dispersed in green friendly water environments. The FGO was successfully fabricated by simple hydrot...
Source: Tribology International - July 11, 2019 Category: Materials Science Source Type: research

Design method for suppressing stick-slip using dynamic vibration absorber
In this study, we employed a DVA to suppress the occurrence of stick-slip (SS) generated in sliding systems. By conducting a theoretical analysis and a numerical simulation based on a simplified analytical model, we established a design standard that presents the appropriate design conditions for DVAs to achieve smooth sliding without SS. First, combined with two existing theories: the DVA theory (termed the fixed-points theory) and the SS dynamics theory, the boundary conditions of the occurrence and nonoccurrence of SS were solved. Next, the validity of the boundary solved in this study was confirmed by numerical simulat...
Source: Tribology International - July 11, 2019 Category: Materials Science Source Type: research

Lubricant as a sticking-scale inhibitor on high temperature sliding contact
Publication date: Available online 10 July 2019Source: Tribology InternationalAuthor(s): Bach H. Tran, Kiet Tieu, Shanhong Wan, Hongtao ZhuAbstractSticking oxide scale is one of the most serious concerns on moving steel surfaces at elevated temperature However, there has been limited research dedicated to overcoming this issue. In the present work, pin-on-disc testing was carried out to reveal the effects of lubrication on wear characteristics of High Speed Steel sliding against Stainless Steel 316 at 700 °C. Apart from improved friction behavior, the use of inorganic lubricant significantly inhibits material trans...
Source: Tribology International - July 11, 2019 Category: Materials Science Source Type: research

Regulating interfacial compatibility with amino silane and bio-inspired polydopamine for high-performance epoxy composites
Publication date: Available online 8 July 2019Source: Tribology InternationalAuthor(s): Song Li, Xiao Li, Mingchao Shao, Jingjing Yang, Qihua Wang, Tingmei Wang, Xinrui ZhangAbstractThe poor interfacial compatibility between functional fillers and matrix greatly restricts development of polymer composites. Therefore, in the present paper, carbon fibers (CFs) were modified by biomimetic polydopamine (PDA) and amino silane (KH550) to improve interfacial bonding strength with epoxy (EP) substrate. The grafting of PDA and KH550 was divided into “PDA”, “PDA-KH550” and “(PDA + KH550)&rdquo...
Source: Tribology International - July 9, 2019 Category: Materials Science Source Type: research

Influence of pivot design on nonlinear dynamic analysis of vertical and horizontal rotors in tilting pad journal bearings
Publication date: Available online 6 July 2019Source: Tribology InternationalAuthor(s): Zhaoyang Shi, Yingze Jin, Xiaoyang YuanAbstractThe influence of pivot design on nonlinear dynamic characteristics is investigated for vertical and horizontal rotors. Rocker-back pivot and ball-socket pivot designs are studied. A mathematical model is presented considering Hertzian contact theory for pivot stiffness calculation. Differential diameter effects are also discussed. The pivot design effects on the journal orbits, fluid film thickness and pressure are provided and analyzed. It is shown that pivot design can significantly alter...
Source: Tribology International - July 8, 2019 Category: Materials Science Source Type: research

Hydrodynamic self-lubricating journal bearings analysis using Rabinowitsch fluid lubricant
In this study, the effects of non-Newtonian pseudo-plastic lubricants behavior, using Rabinowitsch fluid model, on static characteristics of circular self-lubricating porous journal bearings of finite length with sealed ends are highlighted. The nonlinear Reynolds equation based on the Rabinowitsch fluid model has been developed specifically for porous journal bearing cases by considering the fluid flow in the porous matrix described by Darcy's law. The Governing equations are discretized using a centered finite difference scheme and solved numerically using an iterative method. Following to the absence of the porous matri...
Source: Tribology International - July 6, 2019 Category: Materials Science Source Type: research