Effect of Heat-Treatment on Microstructure and Thermal Conductivity of Spark-Plasma-Sintered Silicon Nitride Ceramics

抄録

α-Si₃N₄ ceramics were sintered at a low temperature of 1773 K by using a spark-plasma-sintering method. Some of the ceramics were further heat-treated at different temperatures from 1773 K to 2173 K for 1 hour, to study the effect of heat-treatment on the microstructure and the thermal conductivity of the ceramics. The results show that the heat-treatment at temperatures above 1873 K can increase the thermal conductivity greatly. During the heat-treatment, the α-Si₃N₄ transforms into β-Si₃N₄ and the β-Si₃N₄ columnar crystal grows up largely as the heating temperature increases, but the phase transformation and the growth of the β-Si₃N₄ columnar crystal does not seem to have an obvious effect on the thermal conductivity of the ceramics