Electrical and Thermal Properties of SiC Ceramics Sintered with Yttria and Nitrides

The electrical and thermal properties of SiC ceramics containing 1 vol% nitrides (BN, AlN or TiN) were investigated with 2 vol% Y2O3 addition as a sintering additive. The AlN-added SiC specimen exhibited an electrical resistivity (3.8 x 10(1) Omega center dot cm) that is larger by a factor of similar to 10(2) compared to that (1.3 x 10(-1) Omega center dot cm) of a baseline specimen sintered with Y2O3 only. On the other hand, BN- or TiN-added SiC specimens exhibited resistivity that is lower than that of the baseline specimen by a factor of 10(-1). The addition of 1 vol% BN or AlN led to a decrease in the thermal conductivity of SiC from 178 W/m center dot K (baseline) to 99 W/m center dot K or 133 W/m center dot K, respectively. The electrical resistivity and thermal conductivity of the TiN-added SiC specimen were 1.6 x 10(-2) Omega center dot cm and 211 W/m center dot K at room temperature, respectively. The present results suggest that the electrical and thermal properties of SiC ceramics are controllable by adding a small amount of nitrides.