检索结果-南通市图书馆

The effect of surface roughness on thermal-elasto-hydrodynamic model of contact mechanical seals

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2013年第10期56卷 1920-1929页

作者： WEN QingFeng LIU Ying HUANG WeiFeng SUO ShuangFu WANG YuMing State Key Laboratory of tribology Tsinghua University

In this paper, the effect of surface roughness on sealing clearance, pressure distribution, friction torque and leakage is studied by the thermal-elasto-hydrodynamic mixed lubrication model. A convergent nominal clearance is formed by the pressure de- formation and thermal deformation of the seal faces. This causes more serious wear in the inner side than that of the outer side of the contact area. Mass leakage increases with the growing of the surface roughness. The temperature and thermal defor- mation on the seal surface increases substantially if the roughness is reduced. The contact mechanical seals have consistent performance when the standard deviation of surface roughness is approximately 0.2 pm. In order to validate the theoretical analysis model, a method combining the measurement of three-dimensioned profile and Raman spectrum is proposed.

关键词： contact mechanical seals mixed lubrication thermal-elasto-hydrodynamic model surface roughness

Wear behavior of WC-Ni sliding against graphite under water lubrication

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第11期33卷 1346-1352页

作者： Gaolong Zhang Ying Liu Yuechang Wang Fei Guo Xiangfeng Liu Yuming Wang The Stare Key Laboratory of tribology Tsinghua University Beijing 100084 China

Wear of hard materials in contact with softer materials is a neglected area of research. However, we observed considerable wear phenomenon at a hard WC-Ni surface sliding over soft graphite under water lubrication. The influences of applied load and the application history on the wear of surface were addressed in our experimental design. Wear of both graphite and WC-Ni surfaces increased with a greater applied load and repeated sliding. The topographies of the worn surfaces showed clear micro-scratches on the hard WC-Ni surface. Scanning electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the abrasive wear of the WC-Ni surface could be attributed to hard WC particles embedded in the graphite surface. These hard particles were formed by shearing of sharp WC-Ni asperities under certain conditions and intrinsic defects of the WC-Ni surface could accelerate this wear process.

关键词： Wear Graphite Cemented carbide

Numerical modeling and analysis of plasmonic flying head for rotary near-field lithography technology

在线全文

学校读者我要写书评

暂无评论

Friction 2018年第4期6卷 443-456页

作者： Yueqiang HU Yonggang MENG State Key Laboratory of tribology Tsinghua University

Rotary near-field lithography(RNFL) technology provides a route to overcome the diffraction limit with a high throughput and low cost for nanomanufacturing. Utilizing the advantage of the passive flying of a plasmonic head, RNFL can achieve a 10 m/s processing speed with a perfect near-field condition at dozens of nanometers. The flying performance of the plasmonic flying head(PFH) is the pivotal issue in the system. The linewidth has a strong correlation with the near-field gap, and the manufacturing uniformity is directly influenced by the dynamic performance. A more serious issue is that the unexpected contact between the PFH and substrate will result in system failure. Therefore, it is important to model and analyze the flying process of the PFH at the system level. In this study, a novel full-coupled suspension-PFH-air-substrate(SPAS) model that integrates a six-degree of freedom suspension-PFH dynamics, PFH-air-substrate air bearing lubrication, and substrate vibration, is established. The pressure distribution of the air bearing is governed by the molecular gas lubrication equation that is solved by the finite element method(FEM) with a local pressure gradient based adaptive mesh refinement algorithm using the COMSOL Multiphysics software. Based on this model, three designs of the air bearing surface are chosen to study the static, dynamic, and load/unload performance to verify whether it satisfies the design requirements of RNFL. Finally, a PFH analysis solver *** is developed based on the proposed model.

关键词： rotary near-field lithography (RNFL) coupled analysis air bearing finite element method

A comparative study between graphene oxide and diamond nanoparticles as water-based lubricating additives

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2013年第1期56卷 152-157页

作者： LIU YuHong WANG XiaoKang PAN GuoShun LUO JianBin State Key Laboratory of tribology Tsinghua University

The tribological properties of graphene oxide(GO) nanosheets and modified diamond(MD) nanoparticles with excellent water-solubility were *** nanosheets were synthesized using carbon fibers with a regular and uniform size,the lateral size being around 30 nm and the thickness being 2 or 3 nm,while MD nanoparticles were about 30 nm in the three *** friction properties of ceramics were improved by GO nanosheets or MD nanoparticles used as additives in water-based lubrication,though the effects of two nanoparticles were quite *** GO nanosheets,the friction coefficient at the beginning decreased sharply from 0.6 to 0.1,as compared with the dionized water *** the same time,the running-in period was shortened from 2000 s to 250 s.A steady state characterized by ultralow friction(friction coefficient=0.01) was obtained after the running-in *** the case of MD nanoparticles,the friction coefficient stayed at 0.1 without further decrease during the whole *** on the observation of wear scar and characterization of remains on the wear track,the positive effect of GO nanosheets was attributed to their lamellar structure and geometric *** nanoparticles reduced friction by forming the regularly grained surface on the mating surfaces,and prevented further reduction in steady-state friction coefficient owing to their larger size and *** conclusion,GO nanosheets exhibited favorable potential as an effective additive for water-based lubrication.

关键词： graphene oxide diamond lubrication nanoparticles additive

A Comparative Study of Tribological Properties between Perfluoro and Non-perfluoro Alkylsilane Self-assembled Monolayers(SAMs)

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2009年第4期24卷 588-593页

作者：王新宽刘宇宏 State Key Laboratory of tribology Tsinghua University

The tribological properties of perfluoro and non-perfluoro alkylsilane molecular films were investigated and compared detailedly. Their surface properties were characterized by X-ray photoelectron spectroscopy （XPS）, atomic force microscopy （AFM） and contact angle （CA） measurement. A ball-on-disk tribometer was used to study the frictional properties of these alkylsilane monolayers. The experimental results reveal that the alkylsilane molecular films are good candidates to decrease friction and they have good capability to endure rigorous shear forces. Perfluoro alkylsilane molecular films are bonded better with the Si substrate than the simple hydrocarbon ones. The effects of sliding velocity and normal load on friction coefficient are evident and the friction coefficient in- creases with the increase of the sliding velocity. However, friction coefficient decreases with the increase of normal load initially and then increases, indicating there exists a critical normal load for the load effect.

关键词： perfluoroalkylsilane XPS AFM friction coefficient

Laser wavelength effects on(Ti,Al,Si)N in near-field laser nanostructuring by micron optical fiber enhanced irradiation

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2013年第12期56卷 3012-3016页

作者： LIU DaMeng LIU JiaChen WANG Hui SU Kang SHAO TianMin State Key Laboratory of tribology Tsinghua University

The effects of laser wavelengths(1064,532,355 and 266 nm)on nano-processing of fabricating a groove structure on(Ti,Al,Si)N alloy film using the micro-fiber near-field enhanced irradiation are *** is observed that variations of laser wavelength can effectively change the widths of the groove structures,which are featured as one-dimension bowl-like *** minimum of the groove width can be achieved at 293 nm with a 532 nm laser *** order to fabricate the groove in nanoscale,enough energy is delivered onto(Ti,Al,Si)N surface by a single laser *** results are also discussed to understand the experimental results.

关键词： micro-fiber field enhancement nano-optics nanostructuring

Theory analyses and applications of magnetic fluids in sealing

在线全文

学校读者我要写书评

暂无评论

Friction 2023年第10期11卷 1771-1793页

作者： Decai LI Yanwen LI Zixian LI Yuming WANG State Key Laboratory of tribology Tsinghua UniversityBeijing100084China

Magnetic fluids are the suspensions composed of magnetic nanoparticles,surfactants,and non-magnetic carrier *** fluids are widely used in various fields,especially in sealing,because of their excellent features,including rapid magnetic response,flexible flow ability,tunable magneto-viscous effect,and reliable self-repairing ***,we provide an in-depth,comprehensive insight into the theoretical analyses and diverse applications of magnetic fluids in sealing from three categories:static sealing,rotary sealing,and reciprocating *** summarize the magnetic fluid sealing mechanisms and the development of magnetic fluid seals from 1960s to the present,particularly focusing on the recent progress of magnetic fluid *** magnetic fluid sealing technology has been commercialized and industrialized,many difficulties still exist in its *** the end of the review,the present challenges and future prospects in the progress of magnetic fluid seals are also outlined.

关键词： magnetic fluid sealing mechanism static sealing rotary sealing reciprocating sealing

A sulfonated modification of PEEK for ultralow friction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2023年第6期11卷 881-893页

作者： Shihua YUAN Chenhui ZHANG State Key Laboratory of tribology Tsinghua UniversityBeijing100084China

Polyether ether ketone(PEEK)is a widely used material for friction pairs due to its excellent mechanical strength,good wear resistance,and chemical ***,some modifications are necessary when PEEK is used as a water-lubricated friction *** this study,a novel sulfonation method was developed to design a water-lubricated friction pair with ultralow friction,good wear resistance,and high loading *** powders were sulfonated using ClSO3H and sintered to form bulk *** sulfonated PEEK(SPEEK)plastic exhibited good tribological *** a low sliding speed,the friction coefficient was smaller than 0.02 when a 3 wt% NaCl solution was used as the *** order of magnitude of the wear rate was as low as 10^(-8) mm^(3)/(N·m).The mechanism of friction reduction was mainly hydration *** negatively charged -SO_(3)^(-) groups on the friction pair can adsorb hydrated Na+cations by electrostatic *** hydrated Na+cations have a high load capacity and low shearing *** ultralow wear mechanism observed in this study is possibly due to ultralow friction properties of the friction pairs prepared through the proposed sulfonation and thermoforming procedures.

关键词： polyether ether ketone(PEEK) sulfonation hydration lubrication friction wear

Advancements in superlubricity

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2013年第12期56卷 2877-2887页

作者： LI JinJin LUO JianBin State Key Laboratory of tribology Tsinghua University

Superlubricity is a new area in tribology,in which the slide friction coefficient is about 1/1000 to 1/100 of the general *** the concept of superlubricity was proposed,it has attracted more and more attentions from researchers in fields of tribology,physics,chemistry,materials,*** significant progresses have been made during the last two decades in experimental studies on *** the present work,the recent advancements in solid superlubricity and liquid superlubricity are reviewed and the lubricating mechanisms of different superlubricity systems are ***,the problems on the superlubricity mechanism and the development of superlubricity in the future are addressed.

关键词： friction superlubricity solid superlubricating lubricants liquid superlubricating lubricants