Study On The Preparation And Properties Of Al₂O₃-based 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 potassium titanate whiskers under low temperature. The grading methods are applied to find the optimum sintering conditions. Using the MM-200 friction testing machine, the friction behaviors and mechanism of Al₂O₃-based ceramic friction materials are systematically studied, including the effects of different potassium titanate whiskers ratio and different sintering conditions. Furthermore, the microstructure and properties of Al₂O₃-based ceramic are discussed,which offer the experimental references for using Al₂O₃-based ceramic materials as friction materials.The study shows that optimum addition of potassium titanate whiskers is 10%(wt%). The result shows that the properties of the materials have a good performance with the pressure and sintering temperature increasing. The holding time must be suitable. The optimum condition is: sintering tempreature is 1300℃, hot pressing pressure is 10kN, holding time is 1h. The sample has the optimum properties under such condition. The material can get better properties with the addtion of potassium titanate whiskers. Intergranular fracture and intragranular fracture happen to the materials. The materials have crack pinning and crack deflection because of the potassium titanate whiskers which stop the crack. It is one of the most important reasons of better mechanical properties. The wear mechanism of the ceramic friction materials is the pull-out of the grain during the intergranular failure and the transcrystalline fracture. During dry friction, as a result of the interactions, the cracks which destroy the materials appear around the porosity.