Study On Friction And Wear Behaviors Of WC-Al₂O₃ Composite

Cmented carbide with high hardness, wear resistance and a series of advantages,which is indispensable materials in modern industry. Cemented carbide is composed of refractory metal and metal binder. And made by powder metallurgy. Typically the metal compound is tungsten carbide?wc?,titanium carbide?Tic?,etc.,metal drill as a binder. However, Co as a scarce and expensive metal, Research both low cost and high hardness and high toughness of WCbased cemented carbide having a realistic application significance. Donghua University through the efforts to prepare a high hardness and high toughness material of WC-Al2O₃ composite with cobalt-free.In this paper, WC-Al2O₃, WC-6Co and WC-Al2O₃-Y2O₃, slid against with WC-6Co hard alloy, and conduct a systematic study for these materials, analysis and discuss the friction and wear mechanism of the composites.Temperature, Speed and load as the main factors to conduct test with spherical surface contact friction mode, Obtain the friction coefficient and wear loss of different composites with the change of load, temperature and speed. And the morphological analyses of the worn surface were made by SEM, and ultra-depth microscope and surface composition of the materials were analyzed by X diffraction instrument. The results show that:the friction coefficient of WC-Al2O₃ reduce with the temperature increase, increase with the speed increase,when the speed and load is constant. The friction coefficient reduce with the load increase when the load from 5N turned to 10 N.The wear loss increase with the temperature improved. The wear mechanism changed to oxidation wear from abrasive wear.Conducted the friction test for WC-6Co hard alloy and compared with WC-Al2O₃ at room temperature, 200?,400?,500?,600?.Due to the presence of Co binder phase,the larger friction coefficient and wear loss of WC-6Co at the room temperature. coefficient is smaller than the WC-Al2O₃,and no significant change of the wear loss with the temperature arise,the friction.the wear mechanism is that the worn surface occurs plastic deformation, and then result in small cracks, made the hard phase of WC off, and form pitting. with temperature arise, due to the cobalt oxidation inhibit WC oxide. Wear mechanism is abrasive wear with the temperature arise, accompanied by a slight oxidation wear,. when the temperature rose exceed 500 ?.The friction coefficient of WC-Al2O₃-Y2O₃ decrease with the temperature increase, with the speed increase. The friction coefficient smaller than WC-Al2O₃ at the condition of 5.25m/min?10.5m/min, however when the speed increased to 21m/min, the friction coefficient is larger than the WC-Al2O₃., the wear loss is small at the low temperature.when the temperature exceed 400?,the wear loss is no difference. The wear mechanism is consistent with WC-Al2O₃.