SiCウイスカー/Si₃N₄セラミック複合材料の機械特性に及ぼす焼結条件の影響

抄録

The influence of sintering temperature and time on mechanical properties was studied for a 20wt% SiC whisker/Si₃N₄ composite. α to β phase transformation of Si₃N₄ was retarded by the whisker incorporation compared to monolithic Si₃N₄, but the delay became smaller with increasing sintering temperature. The bending strength and the fracture toughness increased with increasing sintering temperature from 1700° to 1900°C when sintered for 30min. On the other hand, when the sintering time was extended from 30min to 90min at 1800°C, both the bending strength and the toughness decreased significantly. The behavior of the composite properties can be explained on the basis of the contribution of the matrix microstructure including the content and the size of elongated β grain and the bonding strength between the Si₃N₄ grains and SiC whiskers.