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friction and wear behavior and mechanism of low carbon microalloyed steel containing Nb

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China Foundry 2023年第3期20卷 263-270页

作者： Mei-yi Yuan Jia-cheng Zhang Yi-tao Yang School of Materials Science and Engineering Shanghai UniversityShanghai 200444China

Dry sliding friction and wear test of Nb containing low carbon microalloyed steel was carried out at room temperature,and the effect of Nb on the wear behavior of the steel,as welll as the mechanism was studied.Scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS) were employed to analyze the morphology and composition of the worn surface,and the structure evolution of the plastic deformation layer.The carbide content and type in the steel were analyzed by the electrolytic extraction device and X-ray diffraction(XRD).The experimental results demonstrate that the addition of 0.2% Nb can refine the grain and generate Nb C to improve the wear resistance of the steel.By enhancing the load and speed of wear experiment,the wear mechanism of the test steel with 0.2% Nb changes from slight oxidation wear to severe adhesion wear and oxidation wear.Compared with the load,the increase in the rotation speed exerts a greater influence on the wear of the test steel.

关键词： Nb content low carbon microalloyed steel friction and wear carbide

friction and wear behaviors of a gradient nano-grained AISI 316L stainless steel under dry and oil-lubricated conditions

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Journal of Materials Science & Technology 2018年第10期34卷 1835-1842页

作者： P.F. Wang Z. Han Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China University of Chinese Academy of Sciences Beijing 100049 China

A gradient nano-grained （GNG） surface layer was fabricated on an AIS1316L stainless steel （SS） by using the surface mechanical rolling treatment （SMRT）. Reciprocating dry and oil-lubricated sliding tests of the GNG 316L SS in air at room temperature were conducted in comparison with the coarse-grained （CG） counterpart. Worn surface morphologies and subsurface microstructures were investigated for both 316L SS samples. 316L SS with a GNG surface layer shows a significantly improved wear resistance, especially under oil-lubricated condition. The notably wear resistance enhancement of the GNG 316L SS is attributed to the GNG surface layer with high strain accommodation ability and high hardness, which can reduce the wear volume in the running-in stage effectively.

关键词： Austenitic stainless steel Gradient nano-grained surface layer friction and wear Running-in

friction and wear Behavior of AlTiN-Coated Carbide Balls Against SKD11 Hardened Steel at Elevated Temperatures

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Acta Metallurgica Sinica(English Letters) 2018年第10期31卷 1073-1083页

作者： Rui Wang Hai-Juan Mei Ren-Suo Li Quan Zhang Teng-Fei Zhang Qi-Min Wang School of Electromechanical Engineering Guangdong University of Technology Guangzhou 510006 China School of Mechanical Engineering Guilin University of Aerospace Technology Guilin 541004 China

In this study, AlTiN coatings were deposited on YT14 cemented carbide balls by arc ion plating technique. The friction and wear behavior of the AlTiN-coated balls against SKD11 hardened steel was investigated by sliding tests using a ball-ondisk tribometer at various temperatures from 25 to 700 ℃ in air. The results showed that the friction and wear behavior was significantly influenced by the testing temperature. Obvious fluctuations were observed in the friction curves at elevated temperatures, which could be attributed to the formation and rupture of unstable Fe and Cr oxide layers. As the temperature increased from 25 to 500 ~C, the wear rate of the coated balls increased from the scale of 10-21-10-20 m3/ N m, and then decreased to 10-22 m3/N m as the temperature further increased to 700℃. It was also found that the friction and wear behavior of the coated balls was directly dependent on the counterpart materials. As the temperature increased, the main wear mechanism of the coated balls changed from mild abrasive wear and adhesive wear to abrasive wear failure at 500℃, and then transferred to adhesive wear and mild oxidation wear at 700℃. For SKD11 hardened steel, the primary wear mechanism changed from delamination wear to abrasive wear and then transferred to plastic deformation and fatigue wear, accompanied by adhesive wear and tribo-oxidation wear.

关键词： AlTiN. SKD11 hardened steel. Elevated temperatures friction and wear

friction and wear behavior of Mg–11Y–5Gd–2Zn–0.5Zr(wt%)alloy with oil lubricant

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Rare Metals 2013年第5期32卷 453-458页

作者： Li-Jie Cao Qu-Dong Wang Yu-Juan Wu Bing Ye College of Mechanical Engineering Shanghai University of Engineering Science National Engineering Research Center of Light Alloy Net Forming Shanghai Jiao Tong University

The sliding friction and wear behaviors of Mg-11Y-5Gd-2Zn-0.5Zr （wt%） alloy were investigated under oil lubricant condition by pin-on-disk configuration with a constant sliding distance of 1,000 m in the temperature range of 25-200℃. Results indicate that the volumetric wear rates and average friction coefficients decrease with the increase of sliding speeds, and increase with the increase of test temperature below 150℃. The hard and thermally stable Mg12（Y,Gd）Zn phase with long-period stacking order structure in the alloy presents significant wear resistance, The wear mechanism below 100℃ is abrasive wear as a result of plastic extrusion deformation. The corporate effects of severe abrasive, oxidative, and delaminating wear result in the tribological mechanism above 100℃.

关键词： Mg-11Y-5Gd-2Zn-0.5Zr alloy Long-period stacking order （LPSO） structure Lubricated friction and wear

friction and wear Characteristics of Mg-Al Alloy Containing Rare Earths

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Journal of Rare Earths 2003年第2期21卷 157-162页

作者：祁庆琚刘勇兵杨晓红 College of Materials Science and Engineering Jilin University

The influence of rare earth on the friction and wear characteristics of magnesium alloy AZ91 and AM60 were studied. The results show that the wear resistance properties of rare earth magnesium alloys are better than those of matrix alloy under the testing conditions. The anti wear behaviour of AZ91 alloy is much better than that of AM60 alloy. In dry sliding process,magnesium alloys undergo a transition from mild wear to severe wear. The addition of rare earths refine the structure of alloys, improve the comprehensive behaviors of magnesium alloys, increase the stability of oxidation films on worn surfaces, enhance the loading ability of rare earth magnesium alloys, and delay the transition from mild wear to severe wear effectively.

关键词： metal materials magnesium alloy friction and wear rare earths

Tribological properties of PTFE-based fabric composites at cryogenic temperature

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friction 2024年第2期12卷 245-257页

作者： Mingkun XU Zidan WANG Lihe GUO Liming TAO Tianbao MA Tingmei WANG Qihua WANG Key Laboratory of Science and Technology on wear and Protection of Materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Fabric composites are widely employed in self-lubricating bearing liners as solid lubrication materials.Although the tribological behaviors of fabric composites have been extensively studied,the cryogenic tribological properties and mechanisms have been scarcely reported and are largely unclear to instruct material design for aerospace and other high-tech applications.Herein,the tribological properties of polytetrafluoroethylene(PTFE)-based hybrid-fabric composites were investigated at cryogenic and ambient temperatures in the form of pin-on-disk friction under heavy loads.The results suggest that the friction coefficients of the hybrid-fabric composites obviously increase with a decrease in wear when the temperature drops from 25 to−150°C.Moreover,thermoplastic polyetherimide(PEI),as an adhesive for fabric composites,has better cryogenic lubrication performance than thermosetting phenol formaldehyde(PF)resin,which can be attributed to the flexible chemical structure of PEI.The excellent lubrication performance of hybrid-fabric composites is attributed to the transfer film formed by PTFE fibers on the surface of fabrics.

关键词： cryogenic temperatures fabric composites friction and wear transfer film

Tribological properties of low-temperature time-dependent pretreated graphite for mechanical seal pairs in high-speed turbopump

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friction 2024年第2期12卷 305-318页

作者： Yangyang ZHAO Guoyuan ZHANG Junqian WANG He WANG Weigang ZHAO Qunfeng ZENG School of Mechano-Electronic Engineering Xidian UniversityXi’an 710071China Xi’an Aerospace Propulsion Institute Xi’an 710071China Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong UniversityXi’an 710049China

The friction coefficient and wear rate of pretreated graphite with liquid nitrogen were obtained by using a ball-on-disk tester,and the wear of GCr15–graphite seal pairs with the low-temperature time-dependent pretreatment was discussed by comparing the wear morphology.The results show that liquid nitrogen pretreatment can affect the hardness and interlayer spacing of graphite.The range of the friction coefficients of pretreated graphite changes from 0.17 to 0.22.With the increase of liquid nitrogen pretreatment time,the wear mechanism of graphite would change from dominated three-body wear to adhesion wear.The experimental results of the mechanical seal with liquid nitrogen pretreatment show that the wear rate of stator is less than 0.00165 mm^(3)·N^(−1)·m^(−1),and the graphite shows a good low-temperature compatibility.

关键词： graphite low-temperature pretreatment mechanical seal friction and wear

Molecular design of recyclable thermosetting polyimide and its composite with excellent mechanical and tribological properties

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friction 2024年第3期12卷 452-461页

作者： Xiaoyue WANG Zenghui YANG Tingmei WANG Qihua WANG Xinrui ZHANG Song LI Key Laboratory of Science and Technology on wear and Protection of Materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were successfully synthesized.The tensile strength,elongation at break,and Young’s modulus of PI are 108.70±7.29 MPa,19.35%±3.89%,and 2336.42±128.00 MPa,respectively.The addition of reduced graphene oxide(RGO)not only enhances the mechanical properties of PI but also endows it with excellent tribological properties.The PI illustrates a high recycling efficiency of 94.15%,but the recycled composite exhibits inferior mechanical properties.The recycling and utilization of PI and its composite are realized through imine bonds(-C=N),which provides new guidance for solving the problem of environmental pollution and resource waste and is potential application in the field of sustainable tribology.

关键词： thermosetting polyimide(PI) recyclability dynamic covalent bonds friction and wear polymer composites

Erosion Characteristics of Oil-immersed On-load Tap Changer Contacts Under Varying Contact Speeds and Pressures

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Chinese Journal of Electrical Engineering 2024年第1期10卷 21-34页

作者： Zongying Li Shuaibing Li Yongqiang Kang Zheng Li Hongwei Li School of New Energy and Power Engineering Lanzhou Jiaotong UniversityLanzhou 730070China School of Electrical Engineering Southwest Jiaotong UniversityChengdu 611756China School of Automation and Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China

With the growing demand for precise voltage adjustment and reactive regulation,the frequent operation of on-load tap changers(OLTCs)in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching process.This erosion causes significant wear on the contacts,thereby reducing their lifespan.Therefore,the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed OLTCs.To achieve this,a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact pressures.Additionally,finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc energy.The surface morphology of the contacts was observed using an optical microscope.The findings revealed that as the sliding speed increased,the arc energy,arc initiation rate,and contact resistance initially exhibited an upward trend,then decreased,and eventually increased again.The minimum values were observed at a sliding speed of 90 mm/s.Moreover,the arc energy,arc initiation rate,and contact resistance decreased gradually as the contact pressure increased.After reaching a contact pressure of 1.5 N,the variation in the arc energy stabilized.At lower contact pressures,arc erosion dominated the wear on the contact surface.However,at higher contact pressures,the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc erosion.In summary,experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion,contact resistance,and surface damage of OLTC contacts in oil-immersed systems.

关键词： Oil-immersed on-load tap changer arc energy contact resistance friction and wear arc erosion