Columnar inter-grains and toughening of SiC-AlN ceramics induced by addition of α-SiC

摘要

The fabrication of SiC-AlN solid solutions with columnar inter-grains using the addition of small amounts of α-SiC to an AlN- β-SiC mix was studied by hot-pressing under 2030 deg C. The appreciable amounts of the α-SiC content for a reaction of AlN and β -SiC affected the SiC-AlN phase relationships and the microstructures by stabilizing a 2H phase. It could develop columnar inter-grains of 4H phase and the stable 2H phase with a uniform composition and grain size distributions. The α-sic containing samples showed fracture toughness of 5.1-5.4 Map m~1/2. The fracture toughness was related to the amounts of 4H present. The enhanced fracture toughness was due to the reinforcement of the columnar inter-grains of 4H phase in the 2H phase induced by appreciable amounts of α-SiC.