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MoS_(2) reinforced PEEK composite for improved aqueous boundary lubrication

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Friction 2023年第9期11卷 1660-1672页

作者： Xin HOU Pengpeng BAI Jingyang LI Yuanzhe LI Hui CAO Xiangli WEN Yonggang MENG Liran MA Yu TIAN State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

Polyether-etherketone(PEEK)is a corrosion-resistant material that has been widely used in aqueous ***,its anti-wear performance must be improved for its application in the *** this study,to improve the anti-wear performance of PEEK for aqueous boundary lubrication,PEEK/MoS_(2)composites were prepared by ball-milling and spark plasma sintering processes.A competitive MoS_(2)mechanism between the low shear strength property and the role of promoting wear debris generation influences the anti-wear performance of PEEK/MoS_(2)*** demonstrated that the coefficients of friction(COF)and wear rate of PEEK composite with 0.25 wt%MoS_(2)were significantly reduced 68%and 94%,***,this was the first time that a PEEK composite could achieve a COF of less than 0.05 in aqueous boundary *** anti-wear performance was verified to be better than that of PEEK/carbon fiber(CF)and Thordon *** PEEK/MoS_(2)composite may be a potential material for underwater equipment because of its outstanding anti-wear performance in aqueous boundary lubrication.

关键词： polyether-etherketone(PEEK)composite MoS_(2) anti-wear performance aqueous lubrication boundary lubrication

Molecular dynamics simulation of the Stribeck curve: boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level

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Friction 2023年第12期11卷 2342-2366页

作者： Simon STEPHAN Sebastian SCHMITT Hans HASSE Herbert M.URBASSEK Laboratory of Engineering Thermodynamics(LTD) Department of Mechanical and Process EngieeringTU KaiserslauternRheinland-Pfalz 67663Germany Physics Department and Research Center(OPTIMAS) TU KaiserslauternRheinland-Pfalz 67663Germany

Lubricated contact processes are studied using classical molecular dynamics simulations for determining the entire range of the Stribeck ***,the lateral movement of two solid bodies at different gap height are *** each simulation,a rigid asperity is moved at constant height above a flat iron surface in a lubricating *** methane and decane are considered as *** three main lubrication regimes of the Stribeck curve and their transition regions are covered by the study:boundary lubrication(significant elastic and plastic deformation of the substrate),mixed lubrication(adsorbed fluid layer dominates the process),and hydrodynamic lubrication(shear flow is set up between the surface and the asperity).We find the formation of a tribofilm in which lubricant molecules are immersed into the metal surface—not only in the case of scratching,but also for boundary lubrication and mixed *** formation of a tribofilm is found to have important consequences for the contact ***,the two fluids are found to show distinctly different behavior in the three lubrication regimes:For hydrodynamic lubrication(large gap height),decane yields a better tribological performance;for boundary lubrication(small gap height),decane shows a larger friction coefficient than methane,which is due to the different mechanisms observed for the formation of the tribofilm;the mixed lubrication regime can be considered as a transition regime between the two other ***,it is found that the nature of the tribofilm depends on the lubricant:While methane particles substitute substrate atoms sustaining mostly the crystalline structure,the decane molecules distort the substrate surface and an amorphous tribofilm is formed.

关键词： boundary lubrication mixed lubrication hydrodynamic lubrication molecular dynamics simulation tribofilm

Comparative study on boundary lubrication of Ti_(3)C_(2)T_(x) MXene and graphene oxide in water

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Friction 2023年第9期11卷 1641-1659页

作者： Wei SUN Qingrui SONG Kun LIU Qing ZHANG Zhensheng TAO Jiaxin YE Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230009China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China

The emerging use of two-dimensional(2D)nanomaterials as boundary lubricants in water offers numerous benefits over oil-based lubricants;whereas the friction reduction varies significantly with nanomaterial type,size,loading,morphology,*** oxide(GO)and Ti_(3)C_(2)T_(x)MXene,a relatively new 2D material,are investigated as boundary lubricants in water in this *** contact pair mainly includes Si3N4 balls and Si *** results found(1)monodispersed GO offers better lubricity than monodispersed MXene under identical concentration and testing conditions;and(2)the mixed dispersion of GO and MXene(0.1 mg/ml:0.1 mg/ml)produced the lowest friction coefficient of~0.021,a value 4×and 10×lower than that produced by comparable mono-dispersions of GO or MXene,*** track analysis,focused ion beam microscopy,in-situ contact observation,and atomic force microscopy(AFM)characterization suggest(1)GO nanoflakes have higher adhesion than MXene and are more easily adsorbed on the tribopairs’surfaces,and(2)GO/MXene tribofilm has a layered nanostructure constituting GO,MXene,amorphous carbon,and TiO_(2).We further hypothesized that the high lubricity of GO/MXene results from the synergy of GO’s high adhesiveness,MXene’s load support ability,and the low shear strength of both *** present study highlights the key role of tribofilm stability in water-based boundary lubrication using state-of-the-art 2D nanomaterials.

关键词： Mxene graphene oxide water-based lubricant additives boundary lubrication adsorption film

Synergistic tribological effect between polyisobutylene succinimide-modified molybdenum oxide nanoparticle and zinc dialkyldithiophosphate for reducing friction and wear of diamond-like carbon coating under boundary lubrication

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Friction 2023年第11期11卷 2021-2035页

作者： Shuoshuo CHEN Ningning SONG Shengmao ZHANG Yujuan ZHANG Laigui YU Pingyu ZHANG National&Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials Henan UniversityKaifeng 475004China

Organic molybdenum lubricant additive like molybdenum dialkyl dithiocarbamate(MoDTC)can cause wear acceleration of diamond-like carbon(DLC)coating coupled with steel under boundary lubrication,which hinders its industrial ***,polyisobutylene succinimide(PIBS),an organo molybdenum amide,was adopted to modify molybdenum oxide affording molybdenum polyisobutylene succinimidemolybdenum oxide nanoparticles(MPIBS-MONPs)with potential to prevent the wear acceleration of DLC *** thermal stability of MPIBS-MONPs was evaluated by thermogravimetric *** tribological properties as the additives in di-isooctyl sebacate(DIOS)were evaluated with MoDTC as a control;and their tribomechanism was investigated in relation to their tribochemical reactions and synergistic tribological effect with zinc dialkyldithiophosphate(ZDDP)as well as worn surface *** indicate that MPIBS-MONPs/ZDDP added in DIOS can significantly reduce the friction and wear of DLC coating,being much superior to *** is because MPIBS-MONPs and ZDDP jointly take part in tribochemical reactions to form a composite tribofilm that can increase the wear resistance of DLC ***,the molybdenum amide on MPIBS-MONPs surface can react with ZDDP to form MoS2 film with excellent friction-reducing ability;and MPIBS-MONPs can release molybdenum oxide nanoparticle to form deposited lubrication layer on worn *** as-formed composite tribofilm consisting of molybdenum oxide nanocrystal,amorphous polyphosphate,and molybdenum disulfide as well as a small amount of Mo2C accounts for the increase in the wear resistance of DLC coating under boundary lubrication.

关键词： molybdenum oxide nanoparticle zinc dialkyldithiophosphate(ZDDP) synergistic tribological effect diamond-like carbon(DLC)coating boundary lubrication wear resistance

Effects of surface nanostructure on boundary lubrication using molecular dynamics

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Nanotechnology and Precision Engineering 2021年第3期4卷 54-62页

作者： Ling Pan Hui Yu Shiping Lu Guobin Lin School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350116China

Molecular dynamics simulations are used to study the boundary lubrication behaviors of squalane lubricant between two iron wall structures during shearing at different pressures and *** lubrication models with a smooth iron wall and a nanostructured iron wall,respectively,are constructed,and the density distribution of the lubricating film and the velocity distribution in the shearing process are *** mechanical response of the solid wall is output,and the friction coefficient is calculated.A tribological test is performed with a UMT-2 tribometer under sliding conditions to evaluate the reliability of the simulation *** results show that the surface nanostructure has a significant effect on the film thickness and delamination of the lubricating film but little effect on the velocity distribution of the lubricating *** nano strip groove helps to reduce the friction coefficient of the boundary lubrication system.

关键词： boundary lubrication Rough surface Molecular dynamics Lubricating film Friction coefficient

boundary lubrication BETWEEN Cr2O3-COATED CYLINDER LINER AND Mo-COATED PISTON RING AT HIGH TEMPERATURE

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Progress in Natural Science:Materials International 1992年第6期 512-523页

作者：金元生曹立礼夏为民马晓华 Beijing 100084 National Tribology Laboratory Tsinghua University PRC

The present paper introduces some of our research results in the field of friction and lubricationat high *** temperature friction test indicates that Cr2O3-coated cylinder liner matchingMo-coated piston ring shows excellent antifriction behaviour at high temperature under lubrication byan all-synthetic ethers/esters oil with a complex *** further surface analysis with SEM,WDS,XPS,*** that some solid lubrication mechanisms exist at the interface between Cr2O3liner and Mo alloy *** Mo alloy phase in piston ring surface reacts with chemical compoundcontaining sulphur in the complex additive forming MoS2films;the flee carbon produced by catalyticcracking of hydrocarbon in the lubricating oils is transformed into graphite by the effect of high temper-ature and high *** synergistic effect of graphite on MoS2films induces high temperaturelubrication very well and the coefficient of friction decreases to as low as about 0.045.

关键词： boundary lubrication solid lubrication high temperature friction

boundary slip and lubrication mechanisms of organic friction modifiers with effect of surface moisture

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Friction 2024年第7期12卷 1483-1498页

作者： Xiaobin YI Haiyu XU Ge JIN Yang LU Biqiang CHEN Shaofeng XU Junqin SHI Xiaoli FAN State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Xi’an Thermal Power Research Institute Co. Ltd.Xi’an 710054China NingboTech University Ningbo 315000China

Surface moisture or humidity impacting the lubrication property is a ubiquitous phenomenon in tribological systems,which is demonstrated by a combination of molecular dynamics(MD)simulation and experiment for the organic friction modifier(OFM)-containing *** stearic acid and poly-α-olefin 4cSt(PAO4)were chosen as the OFM and base oil molecules,*** physical adsorption indicates that on the moist surface water molecules are preferentially adsorbed on friction surface,and even make OFM adsorption film thoroughly leave surface and mix with base *** shear process,the adsorption of water film and desorption OFM film are further enhanced,particularly under higher shear *** simulated friction coefficient(that is proportional to shear rate)increases firstly and then decreases with thickening water film,in good agreement with experiments,while the slip length shows a contrary *** wear increases with humidity due to tribochemistry revealing the continuous formation and removal of Si–O–Si *** tribological discrepancy of OFM-containing lubricant in dry and humid conditions is attributed to the slip plane’s transformation from the interface between OFM adsorption film and lubricant bulk to the interface between adsorbed water *** work provides a new thought to understand the boundary lubrication and failure of lubricant in humid environments,likely water is not always harmful in oil lubrication systems.

关键词： organic friction modifier(OFM) boundary lubrication boundary slip surface moisture

boundary-lubricated biomaterials with drug delivery for osteoarthritis treatment

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Friction 2024年第10期12卷 2167-2187页

作者： Junyu WU Kaixuan REN Jingbo YIN Department of Polymer Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The good lubrication ability of articular cartilage holds significant importance in our daily ***(OA),the most prevalent degenerative joint disease,causes cartilage damage,increased friction,and ***,the current clinical treatments for OA exhibit some ***,the sustained drug release systems with lubricating function have attracted considerable attention for treating *** review introduces the lubrication mechanism of cartilage,focusing particularly on the boundary lubrication *** research progress of boundary-lubricated biomaterials with drug delivery,including microcarriers,hydrogels,and nanoparticles in the treatment of OA by improving inter-articular lubrication and relieving inflammation is discussed and *** efficacy and challenges of boundary-lubricated biomaterials with drug delivery in the treatment of OA are summarized,and the prospects are also discussed.

关键词： osteoarthritis joint friction boundary lubrication hydration lubrication drug delivery

Molecules with a TEMPO-based head group as high-performance organic friction modifiers

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Friction 2023年第2期11卷 316-332页

作者： Jinchi HOU Masaki TSUKAMOTO Seanghai HOR Xingyu CHEN Juntao YANG Hedong ZHANG Nobuaki KOGA Koji YASUDA Kenji FUKUZAWA Shintaro ITOH Naoki AZUMA Department of Complex Systems Science Graduate School of InformaticsNagoya UniversityNagoya 464-8601Japan Institute of Materials and Systems for Sustainability Nagoya UniversityNagoya 464-8601Japan Department of Micro-Nano Systems Engineering Graduate School of EngineeringNagoya UniversityNagoya 464-8603Japan

High-performance organic friction modifiers(OFMs)added to lubricating oils are crucial for reducing energy loss and carbon *** establish a new class of OFMs,we measured the friction and wear properties of N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)dodecaneamide referred to as *** effect of its head group chemistry,which is characterized by a rigid six-membered ring sandwiched by an amide group and a terminal free oxygen radical,was also investigated with both experiments and quantum mechanical(QM)*** measurement results show that C12Amide-TEMPO outperforms the conventional OFMs of glyceryl monooleate(GMO)and stearic acid,particularly for load-carrying capacity,wear reduction,and stability of friction over *** friction and wear reduction effect of C12Amide-TEMPO is also greatly superior to those of C12Ester-TEMPO and C12Amino-TEMPO,in which ester and amino groups replace the amide group,highlighting the critical role of the amide *** QM calculation results suggest that,in contrast to C12Ester-TEMPO,C12Amino-TEMPO,and the conventional OFMs of GMO and stearic acid,C12Amide-TEMPO can form effective boundary films on iron oxide surfaces with a unique double-layer structure:a strong surface adsorption layer owing to the chemical interactions of the amide oxygen and free radical with iron oxide surfaces,and an upper layer owing to the interlayer hydrogen-bonding between the amide hydrogen and free radical or between the amide hydrogen and ***,the intralayer hydrogen-bonding in each of the two layers is also *** suggest that in addition to strong surface adsorption,the interlayer and intralayer hydrogen-bonding also increases the strength of the boundary films by enhancing the cohesion strength,thereby resulting in the high tribological performance of *** findings in this study are expected to provide new hints for the optimal molecular design of OFMs.

关键词： organic friction modifiers(OFMs) TEMPO friction and wear surface adsorption molecular reactivity boundary lubrication