Study On The Fabrication And Properties Of Al₂O₃/SiC Ceramic Composites

Al₂O₃ ceramic is one of the most intensive study structural ceramics,with high mechanical strength,insulation resistance,wear resistance,corrosion resistance,high temperature resistance and its light weight,low cost,etc.,also with the electrical properties, optical properties and so on.However,its low fracture toughness greatly limits its application and development.In recent years,researchers are working on toughening through addition of secondphase.In this paper,Al₂O₃/SiC nano-/micro-sized composties have been prepared through adding micro-sized SiC particles with wide grain-size distribution(0.1μm-1.9μm) and polycarbosilane in-situ reaction derived nano-SiC particles into Al₂O₃ by hot pressing at 1635℃.Mechanical properties including Vickers hardness,fracture toughness,flexural strength,wear resistance and microstructure are analyzed.The effects of different adding methods on the performance and micro-structure are studied.The toughening and strengthening mechanisms are analyzed.Through direct adding second SiC particles,Al₂O₃/SiC composite ceramics with different contents of 0-20 wt.%SiC have been prepared,the maximum fracture toughness of 7.6MPa·m^1/2 is obtained when SiC content is 5wt.%by indentation method.The maxium flexural strength of 459.7MPa is obtained when SiC content is 20wt.%.Compared with monolithic alumina ceramic,mechanical properties are improved significantly.PCS in-situ generated SiC is nano-level,addition of nanoparticles is an effective way to improve the performance of Al₂O₃/SiC composites.The fracture toughness and flexural strength reach maximum of 5.9MPa·m^1/2and 520MPa when PCS derived SiC reaches 10wt.%.