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Song D.,GuangZhou Research Institute of Nonferrous Metals | Qi W.,GuangZhou Research Institute of Nonferrous Metals | Liang T.,Guangzhou Mechanical Engineering Research Institute | Wang H.,GuangZhou Research Institute of Nonferrous Metals | Zhou N.,GuangZhou Research Institute of Nonferrous Metals
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2012

Four groups of friction stir welded 6061-T6 aluminum alloy were artificial aged, and the microstructure and mechanical properties influence law and mechanism of joint with different aging process were investigated by OM and SEM. The results showed the morphology of the weld cross-section constituted of three typical areas. The grain morphology of the weld zone had no significant change by aging treatment, but grain boundaries were more clear and intragranular precipitates increased significantly than the natural aging joint. The joint strength and microhardness improved with the time of artificial aging treatment increased, and the range of improvement gradually decreased with the holding time. The joint exhibited excellent mechanical properties when holding time was 8 h. The tensile strength passed 265 MPa, about 93.0% of the base metal, and nugget zone microhardness reached to 90 HV, about 90% of the base metal. The second phase particles gradually precipitated from matrix which solid solution during the welding process, joint strength and microhardness increased significantly due to dispersion strengthening effect. The precipitate particles reduced gradually with the aging time, and the strengthening effect gradually weakened. The weak area of joint was located in heat affected mechanical zone of retreating side, and the lowest microhardness value was approximately 75% of the base material. The tensile fracture appeared a typical cut-off with an angle of about 45 ° stretched angle and smooth microstructure. The joint fracture dimples of aging treatment exhibited larger and shallower compared with natural aging, and the plastic reduced slightly.


Jia X.,Tsinghua University | Guo F.,Tsinghua University | Huang L.,Guangzhou Mechanical Engineering Research Institute | Salant R.F.,Georgia Institute of Technology | Wang Y.,Tsinghua University
Tribology International | Year: 2013

bstract This study investigates the effects of structure, material parameters and assembly conditions on the reverse pumping rate and friction torque of the radial lip seal by using a mixed elastohydrodynamic lubrication model. The orthogonal array method is used to make a numerical experiment plan for eight parameters, which are identified as eight control factors. Each factor has five levels. The significance of each parameter on the reverse pumping rate and friction torque of the radial lip seal is evaluated by range analysis and F-test. As a result, optimal values of eight parameters are suggested. The seal with this set of optimal values has a higher reverse pumping rate and lower friction torque than those of a previously-designed seal. © 2013 Elsevier Ltd.


Guo F.,Tsinghua University | Jia X.,Tsinghua University | Huang L.,Tsinghua University | Huang L.,Guangzhou Mechanical Engineering Research Institute | And 2 more authors.
Polymer Degradation and Stability | Year: 2013

Since aging is an inevitable phenomenon during storage of a radial lip seal, this study aims to investigate the effect of aging on the seal performance. An air oven aging test is conducted to produce aged rubber samples and seal products. An aging life prediction model is constructed to predict the equivalent material properties at any storage temperature. The material property parameters of aged rubber samples are measured in a uniaxial compression experiment. The pumping rate and friction torque of the seal are calculated through numerical simulation by using a mixed elastohydrodynamic lubrication (EHL) model. A bench test is used to verify the aging life prediction model and the simulation results of the EHL model. Finally, the verified EHL model is used to study how aging during storage affects the lip seal performance, as characterized by the leakage and friction torque. © 2013 Elsevier Ltd. All rights reserved.


Guo F.,Tsinghua University | Jia X.,Tsinghua University | Huang L.,Tsinghua University | Huang L.,Guangzhou Mechanical Engineering Research Institute | Wang Y.,Tsinghua University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2014

A mixed lubrication model of rotary lip seals using a statistical approach with flow factors based on reverse pumping mechanism has been developed. The model consists of coupled fluid mechanics analysis, asperity contact analysis and deformation analysis. The oil film pressure and shear stress are obtained from solving the Reynolds equation. Using the GREENWOOD-WILLIAMSON surface contact model computes the contact pressure between the lip and shaft. The deformation analysis of lip seals is carried out using the influence coefficient method. Applying the mixed lubrication model to a typical lip seal, the pumping rate and friction torque are the two most important factors of evaluating seal characteristics, which are the output results of theoretical simulation. Most important, the pumping rate and friction torque are measured with bench test designed by the authors. The measurement of these two factors verifies the validity of the mixed lubrication model. For the reverse pumping action of rotary lip seals is resulted from the surface asperities, the influence of roughness on the pumping rate, friction torque and the contact area are carried out by using the verified theoretical mixed lubrication modle. © 2014 Journal of Mechanical Engineering.


Ye S.,South China University of Technology | Zeng X.,Guangzhou Mechanical Engineering Research Institute
Tribology and Lubrication Technology | Year: 2014

The friction and wear properties of polytetrafluoroethylene (PTFE) and its composites with fillers such as bronze, glass fiber, carbon fiber, carbon, graphite, and polymer were studied at ambient temperature and high temperature. The wear resistance and hardness were enhanced by the fillers. Results showed that the wear resistance of all composites was much higher than that of pure PTFE. Pure PTFE has the lowest friction coefficient at ambient temperature (temperature: 23 ± 2°C, humidity: 50 ± 10%) but highest friction coefficient at high temperature (above 100°C). The PTFE composite filled with bronze showed the best wear resistance at ambient temperature but the poorest wear resistance at high temperature. The carbon-graphite- or polymer-filled PTFE composite showed a lower friction coefficient and moderate wear resistance at both ambient and high temperature.


Li M.S.,South China University of Technology | Du Q.G.,Guangzhou Mechanical Engineering Research Institute
Advanced Materials Research | Year: 2014

By the field test, we carried on the physicochemical tests, the lubrication performance test, the ferrographic analysis and ICP tests for different mileage of CVTF, we also ran the electron microscope analysis of the key components of steel belt of CVT's friction pair and bevel pulley. The transformation law of CVTF' lubrication, the inoxidizability, the friction durability friction, the antifriction performance, the attenuation characteristics of functional elements and the abrasion mechanism of Cone wheel and steel belt are investigated.The result showed that there was the presence of extreme pressure film on the surface of friction pair, the physicochemical parameters of CVTF changed very small, the wear metal elements in petrol within 3000km increased slowly. © (2014) Trans Tech Publications, Switzerland.


Li M.S.,South China University of Technology | Li M.S.,Guangzhou Mechanical Engineering Research Institute | Du Q.G.,Guangzhou Mechanical Engineering Research Institute
Applied Mechanics and Materials | Year: 2014

In order to conduct lubricating characteristic analysis on automobile continuously variable transmission, this paper divides overall model of transmission on the basis of the idea of blocking simulation. Then it generates shed oil model of differential mechanism and oil gathering model of oil groove. Set monitoring surface at the position of reverse gear shaft catcher groove in shed oil model of differential mechanism and oil groove in oil gathering model of oil groove to monitor its conditions of oil-taking. Consider the received flow from the two monitoring surfaces in simulation process as evaluation index of effects of transmission lubrication system, as well as conduct quantitative evaluation on lubricating effects of transmission lubrication system. The results show that all of working condition with second gear 1500rpm, reverse gear shaft and oil groove have comparative ideal lubrication effects on input axis. © (2014) Trans Tech Publications, Switzerland.


Sujuan Y.,South China University of Technology | Sujuan Y.,Guangzhou Mechanical Engineering Research Institute | Xingrong Z.,South China University of Technology
Tribology Transactions | Year: 2014

The friction and wear properties of polytetrafluoroethylene (PTFE) and its composites with fillers such as bronze, glass fiber, carbon fiber, carbon, graphite, and polymer were studied at ambient temperature and high temperature. The wear resistance and hardness were enhanced by the fillers. Results showed that the wear resistance of all composites was much higher than that of pure PTFE. Pure PTFE has the lowest friction coefficient at ambient temperature (temperature: 23 ± 2°C, humidity: 50 ± 10%) but highest friction coefficient at high temperature (above 100°C). The PTFE composite filled with bronze showed the best wear resistance at ambient temperature but the poorest wear resistance at high temperature. The carbon-graphite- or polymer-filled PTFE composite showed a lower friction coefficient and moderate wear resistance at both ambient and high temperature. © 2014 Copyright © Society of Tribologists and Lubrication Engineers.


Wang A.,South China University of Technology | Chen L.,South China University of Technology | Jiang D.,South China University of Technology | Zeng H.,Guangzhou Mechanical Engineering Research Institute | Yan Z.,South China University of Technology
Industrial Crops and Products | Year: 2014

We report the design of ionic liquid-in-vegetable oil microemulsion biolubricants which were stabilized by integrated surfactants of 1-octyl-3-methylimidazolium chloride ([C8mim][Cl]) and Triton X-100. Castor oil and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were used as the non-polar and polar phase, respectively. The phase behavior of the pseudo-ternary system at various temperatures was investigated, and the results showed that the addition of [C8mim][Cl] could enhance the driving force of constructing microemulsions, and could further improve their phase formation capacities. Conductivity measurement, dynamic light scattering, UV-vis spectrophotometry, and Fourier transform infrared spectroscopy combined with 1H NMR were used to probe the conformational structure and formation mechanism. A possible structure for the [bmim][BF4]-in-castor oil microemulsion stabilized by mixed surfactants was proposed. In addition, kinematic viscosity, friction, and wear were measured to evaluate the tribological performance of the vegetable oil-based ionic liquid microemulsion biolubricants. The designed systems exhibited enhanced lubricant properties, which indicate promising practical industrial applications. © 2014 Elsevier B.V.


Xiao H.,Hunan University | Li P.,Hunan University | Li P.,Guangzhou Mechanical Engineering Research Institute | Guo D.,Hunan University | And 3 more authors.
Medicinal Chemistry Research | Year: 2014

The reaction of 5,5′-(pyridine-2,6-diyl)bis(4-amino-3-mercapto-1,2,4- triazole) with various carboxylic acid in phosphorus oxychloride yielded the corresponding 2,6-bis(6-substituted-1,2,4-triazolo[3,4-b][1,3,4]thiadiazol-3-yl) pyridine derivatives 6a-l. The structures of the newly synthesized compounds were confirmed by elemental analysis, 1H NMR and 13C NMR spectral, mass spectral, and Infrared spectral studies. All the synthesized target compounds have been investigated for their in vitro antibacterial activity, and the preliminary results revealed that the compounds 6b and 6k exhibited very promising activity against Escherichia coli and Pseudomonas aeruginosa. © Springer Science+Business Media 2013.

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