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Correlation mechanism of friction behavior and topological properties of the contact network during powder compaction

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Particuology 2023年第11期82卷 98-110页

作者： Wei Zhang Chuanniu Yuan Shuai Zhang Weijian Xiao Ning Zhang Rongxin Chen School of Mechanical and Automotive Engineering Fujian University of TechnologyFuzhou350118China

The effect of friction behavior on the compacted density is significant, but the relationship between the topological properties of the contact network and friction behavior during powder compaction remains unclear. Based on the discrete element method (DEM), a DEM model for die compaction was established, and the Hertz contact model was modified into an elastoplastic contact model that was more suitable for metal-powder compaction. The evolution of the topological properties of the contact network and its mechanism during powder compaction was explored using the elastoplastic contact model. The results demonstrate that the friction behavior between the particles is closely related to the topological properties of the contact network. Side wall friction results in smaller clustering coefficient (CC) and excess contact (EC) in the lower region near the side wall. Corresponding to this phenomenon, the upper region near the side wall has more high-stress particles when the major principal stress threshold was considered, and the CC and EC are significantly higher than those in the other regions. This study provides a theoretical basis for improving powder compaction behavior.

关键词： Powdercompaction Granularmatter Discrete element method Topological property friction behavior

High-temperature friction behavior of amorphous carbon coating in glass molding process

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friction 2021年第6期9卷 1648-1659页

作者： Kangsen LI Gang XU Xiaobin WEN Jun ZHOU Feng GONG Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China Shenzhen Kingmag Precision Techonology Co.LTD. Shenzhen 518172China

In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated *** improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron *** friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the ***,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high ***,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction *** friction coefficient between the glass and coating depended on the ***,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition *** work provides a better understanding of the application of carbon coatings in the glass molding.

关键词： glass molding process high temperature friction behavior amorphous carbon coating

friction behavior of Ti-30Fe composites strengthened by TiC particles

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Transactions of Nonferrous Metals Society of China 2021年第4期31卷 988-998页

作者： Sheng-hang XU Jing-wen QIU Hui-bin ZHANG Hua-zhen CAO Guo-qu ZHENG Yong LIU College of Materials Science and Engineering Zhejiang University of TechnologyHangzhou 310014China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Hunan Provincial Key Laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material Hunan University of Science and TechnologyXiangtan 411201China

Ti-Fe-x TiC(x=0, 3, 6, 9, wt.%) composites were fabricated through low temperature ball milling of Ti, Fe and TiC powders, followed by spark plasma sintering. The results show that β-Ti, β-Ti-Fe, η-Ti4 Fe2 O0.4 and TiC particles can be found in the composites. The microstructure can be obviously refined with increasing the content of TiC particles. The coefficient of friction(COF) decreases and the hardness increases with increasing the content of TiC particles. The adhesive wear is the dominant wear mechanism of all the Ti-Fe-x TiC composites. The Ti-Fe-6 TiC composite shows the best wear resistance, owing to the small size and high content of TiC particle as well as relatively fine microstructure. The wear rate of the Ti-Fe-6 TiC composite is as low as 1.869× 10-5 mm3/(N·m) and the COF is only 0.64. Therefore, TiC particle reinforced Ti-Fe based composites may be utilized as potential wear resistant materials.

关键词： TiC particle Ti-Fe based composite powder metallurgy microstructure friction behavior

friction behaviors of the Hot Filament Chemical Vapor Deposition Diamond Film under Ambient Air and Water Lubricating Conditions

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 658-664页

作者： SHEN Bin SUN Fanghong School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China

The friction behavior of the hot filament chemical vapor deposition（HFCVD） diamond film plays a critical role on its applications in mechanical fields and largely depends on the environment. Studies on the tribological properties of HFCVD diamond films coated on Co-cemented tungsten carbide （WC-Co） substrates are rarely reported in available literatures, especially in the water lubricating conditions. In this paper, conventional microcrystalline diamond（MCD） and fine-grained diamond（FGD） films are deposited on WC-Co substrates and their friction properties are evaluated on a reciprocating ball-on-plate tribometer, where they are brought to slide against ball-bearing steel and copper balls in dry and water lubricating conditions. Scanning electron microscopy（SEM）, atomic force microscopy（AFM）, surface profilometer and Raman spectroscopy are adopted to characterize as-deposited diamond films; SEM and energy dispersive X-ray（EDX） are used to investigate the worn region on the surfaces of both counterface balls and diamond films. The research results show that the friction coefficient of HFCVD diamond films always starts with a high initial value, and then gradually transits to a relative stable state. For a given counterface and a sliding condition, the FGD film presents lower stable friction coefficients by 0.02-0.03 than MCD film. The transferred materials adhered on sliding interface are supposed to have predominate effect on the friction behaviors of HFCVD diamond films. Furthermore, the effect of water lubricating on reducing friction coefficient is significant. For a given counterpart, the stable friction coefficients of MCD or FGD films reduce by about 0.07-0.08 while sliding in the water lubricating condition, relative to in dry sliding condition. This study is beneficial for widespread applications of HFCVD diamond coated mechanical components and adopting water lubricating system, replacing ofoil lubricating, in a variety of mechanical processing fields to im

关键词： Hot filament chemical vapor deposition(HFCVD) diamond films friction behavior water lubricating

friction and Wear Performance of Boron Doped, Undoped Microcrystalline and Fine Grained Composite Diamond Films

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Chinese Journal of Mechanical Engineering 2015年第1期28卷 155-163页

作者： WANG Xinchang WANG Liang SHEN Bin SUN Fanghong School of Mechanical Engineering Shanghai Jiao Tong University

Chemical vapor deposition （CVD） diamond films have attracted more attentions due to their excellent mechanical properties. Whereas as-fabricated traditional diamond films in the previous studies don＇t have enough adhesion or surface smoothness, which seriously impact their friction and wear performance, and thus limit their applications under extremely harsh conditions. A boron doped, undoped microcrystalline and fine grained composite diamond （BD-UM-FGCD） film is fabricated by a three-step method adopting hot filament CVD （HFCVD） method in the present study, presenting outstanding comprehensive performance, including the good adhesion between the substrate and the underlying boron doped diamond （BDD） layer, the extremely high hardness of the middle undoped microcrystalline diamond （UMCD） layer, as well as the low surface roughness and favorable polished convenience of the surface fine grained diamond （FGD） layer. The friction and wear behavior of this composite film sliding against low-carbon steel and silicon nitride balls are studied on a ball-on-plate rotational friction tester. Besides, its wear rate is further evaluated under a severer condition using an inner-hole polishing apparatus, with low-carbon steel wire as the counterpart. The test results show that the BD-UM-FGCD film performs very small friction coefficient and great friction behavior owing to its high surface smoothness, and meanwhile it also has excellent wear resistance because of the relatively high hardness of the surface FGD film and the extremely high hardness of the middle UMCD film. Moreover, under the industrial conditions for producing low-carbon steel wires, this composite film can sufficiently prolong the working lifetime of the drawing dies and improve their application effects. This research develops a novel composite diamond films owning great comprehensive properties, which have great potentials as protecting coatings on working surfaces of the wear-resistant and anti-frictional com

关键词： BD-UM-FGCD film HFCVD friction behavior wear performance application

Dry friction Characteristics of Ti-6Al-4V Alloy under High Sliding Velocity

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Journal of Wuhan University of Technology(Materials Science) 2007年第4期22卷 582-585页

作者：邱明 School of Mechatronic Engineering Henan University of Science and Technology Theory of Lubrication and Bearing Institute Xi'an Jiaotong UniversityXi'an 710049China

Tribological behaviours of Ti-6Al-4V alloy pins sliding against GCr15 steel discs over a range of contact pressures （0.33-1.33 MPa） and sliding velocities （30-70 m/s） were investigated using a pin-on-disc tribometer under unlubricated conditions. The wear mechanisms and the wear transition were analyzed based on examinations of worn surfaces using SEM, EDS and XRD. When the velocity increases, the friction coefficient and the wear rate of the Ti-6Al-4V alloy show typical transition features, namely, the critical values of sliding velocities for 0.33 and 0.67 MPa are 60 and 40 m/s, respectively. The experimental results reveal that the tribological behaviours of Ti-6Al-4V alloys are controlled by the thermal-mechanical effects, which connects with the friction heat and hard particles of the pairs. A tribolayer containing mainly Ti oxides and V oxides is formed on the worn surface of Ti-6Al-4V alloy.

关键词： Ti alloy dry sliding friction behavior contact temperature wear mechanism