Authors: Jian Hua Du, Yuan Yuan Li, Xiao Hui Zheng
Abstract: The Cu-based friction materials with nano-graphite were prepared through powder metallurgy technology. The microstructure and friction performance were studied through scan electronic microscope (SEM) and friction tester, respectively. The results indicate that coefficient of the Cu-based friction materials with 2 wt% nano-graphite is high and stable. Comparing with the friction materials without n-C, the wear resistance and heat resistance of the friction materials with nano-graphite has been improved by 11 % and 25 %, respectively. The nano-graphite particles will reduce the abrasive wear and enhance the wear resistance of the Cu-based friction materials.
905
Authors: Yan Tang, Jin Yong Xu, Fang Yong Ye, Cheng Gao, Jing Chun Zhang, Ya Juan Liu
Abstract: To research the tribological properties of micro-arc oxidized ceramic coating in extreme friction condition, ceramic coatings were tested with 1000# waterproof sand paper friction pair for the first time. The phase composition of ceramic coating was analyzed by X-ray diffraction (XRD).Micro structures of ceramic coating surface were observed by scanning electron microscopy (SEM). Friction coefficient of ceramic coating was measured by ball-on-disc wear tester with a 3 mm steel ball. Wear weight loss and wear rate of ceramic coating were measured and calculated by photoelectron balance. The results show that ceramic coatings in various roughnesses have different former wear rates and close wear rates at stable stage. Under water-lubricated condition, wear rate is as low as 0.2 mg/min to 0.3 mg/min. The antiwear behavior of ceramic coating is about 5.3 times compared to aluminium alloy at dry friction. While under water-lubricated condition, the antiwear behavior of ceramic coating improves about 94 times compared to aluminium alloy. The friction coefficient of loose layer is higher than compact layer at dry friction. And there are positive correlation between wear rate and surface roughness of ceramic coating. So it can be verified that compact layer has well antiwear behavior better than loose layer.
1210
Authors: San Ming Du, Yong Ping Niu, Yong Zhen Zhang
Abstract: In the present study, 20 Wt. % ZrO2-Al2O3-17 wt.% TiO2 powders were sprayed using a plasma-spray technique after a NiAl bond layer was deposited on plain carbon steel substrate. The produced coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) including energy-dispersive spectroscopy (EDS). The tribological properties of coatings against hard alloy ball were investigated by using a pin-on-disc tribo-meter under dry environments. The predominant wear mechanism of coating is fatigue.
420
Authors: Ting Xie, Zheng Hua Zhou, Zhen Xing Xu, Jian Wei Yu, Ming Hua Jiao
Abstract: The formed transfer film on the counterpart surface and tribological properties of PTFE composites filled with Al2O3 or SiO2 were investigated in this paper. The results indicated that under the same friction conditions, the friction coefficients of SiO2/PTFE and Al2O3/PTFE are very close to each other, but the wear resistance of SiO2/PTFE is superior to that of Al2O3/PTFE. According to the measured data, the micro-hardness and elastic modulus of the transfer film for SiO2/PTFE are much better than those of Al2O3/PTFE. In addition, the interfacial adhesion strength between the transfer film of SiO2/PTFE and the counterface is higher. It can be proved that the mechanical properties of transfer films for PTFE composites vary with different fillers and the friction transfer film with better adhesion strength and mechanical property is useful to improve the tribological properties of the composite.
172
Authors: Carolyne Oliveira Davi, Miriam K.H. Yassuda, Rosa Maria Rocha
Abstract: Zirconium diboride (ZrB2) is a material of particular interest because of the excellent and unique property combination of high melting point and high electrical and thermal conductivity. In this work, the effect of TiB2 addition on pressureless sintering and hot pressing sintering of ZrB2 was investigated. Four compositions were prepared with 0, 5, 10 and 20 wt% of TiB2. First, ZrB2 and TiB2 powders were milled by planetary mill with SiC spheres at for 4 h and then they were wet mixed. Compacted samples were pressureless sintered at 2150 oC/1h and hot pressed at 1850 °C/30min with 20 MPa, both in Ar atmosphere. The added TiB2 completely dissolved into the structure and formed a solid solution with ZrB2. Addition of TiB2 in ZrB2 ceramic improved densification and hardness for both sintering process, but hot pressed samples exhibited better results.
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