摘要
采用溶胶-凝胶工艺合成的高纯莫来石粉及Tokai碳化硅晶须,以热压方法制备了SiCw/莫来石系复合材料。高纯莫来石陶瓷呈现较高的强度和相当高的断裂韧性,添加SiC晶须后其强度和韧性进一步提高。根据显微结构分析认为,桥联和造成裂纹偏转是晶须的主要增韧机制。清除SiC晶须表层的SiO_2,利于其增韧效应的发挥。
SiCw/mullite composites were prepared by hot pressing using a commercial Tockai-SiC whisker and a kind of highly pure fine mullite powder prepared by sol-gel method. The flexuralstrength and toughness of pure mullite ceramics were 320 MPa and 2.9 MPa. m^(1/2), which werefairly high. The fracture toughness of pure mullite based ceramics was enhanced. significantly by in-coirporation of SiC whisker with crack deflection and whisker bridging being the dominant tougheningmechanisms. Removing SiO_2 on the surface of SiC whisker by acid-leaching appears increase thefracture toughness of the resultant composite. The improvement in fracture toughness is believed to becaused by the lowering of interfacial bonding and the reduction of frictional forces during interfacedebonding and crack deflection.
基金
国家自然科学基金
关键词
莫来石
复合材料
显微结构
增韧性
mullite
silicon carbide
commpites
whiskers
mechanical properties
