Research On Structure And Properties Of Al₂O₃ Ceramic Friction Materials

Along with rapid development of technology, more properties of friction materials are required: Traditional friction materials can't satisfy practical requirements. Therefore, it is important and urgent to develop new kinds of friction materials with excellent properties.Al₂O₃ is a kind of special ceramic with outstanding properties, widely used in industry. Al₂O₃ ceramics and its composites, which have low density, high strength, high wear resistance and chemical stability as well as stable friction coefficient at high temperature, possibly possess of tremendous applied potential in the field of friction materials.In this paper, Al₂O₃-based ceramic friction materials are sintered by Al₂O₃, sintering agent and adding auxiliary materials under normal pressure and low temperature. Using the pin-on-disk friction testing machine ,the friction behaviors and mechanism of Al₂O₃-based ceramic friction materials are systematically studied, including the effects of different raw materials ratio, different forming pressure and additives. Furthermore, the microstructure and properties of Al₂O₃-based ceramic friction materials are discussed by TG-DTA,XRD and SEM, which offer the experimental references for using Al₂O₃-based ceramic materials as friction materials.The study shows that friction coefficient, wear rate and mechanical properties of Al₂O₃-based ceramic materials all have the trend to decrease, with the amount of Al₂O₃ decreasing and the amount of sintering agent increasing.The result shows that density increases and porosity decreases, while friction coefficient and wear rate decreases with the pressure increasing. Fracture toughness property enhances with the pressure increasing .The highest compression strength is obtained at the pressure of 280MPa.Effects of different additives SiC, ZrO₂, CaO and MgO in Al₂O₃ ceramics onstructure and properties of AI2O3 ceramics friction materials have been investigated, and its mechanism is analyzed. Using ZrC>2 and CaO , the extent of friction materials' densification decline, but SiC and MgO have a little effect on densification. Using SiC, MgO and CaO, friction coefficients of the materials decrease. The four additives can all increase the wear resistance , but their mechanisms are different. SiC, ZrO2 and CaO increase the compression strength and fracture toughness property of AI2O3 based ceramic materials, and CaO has obvious function especially.