Thermoelectric Properties of SiC Sintered with Addition of B4C, C and Al2O3

The thermoelectric properties of SiC have been investigated. SiC specimens were prepared from α-SiC powder by sintering at 2100°C with addition of B4C, C and Al2O3. The maximum value of power factor, 9.43×10-4 W/mK2, at 800°C can be obtained for the specimens sintered with 3 mass% of Al2O3 in addition to B4C and C. This value is 30 times larger than that of non-addition specimen. As the reason, the electrical conductivity for the specimen sintered with addition of B4C, C and 3 mass%Al2O3 increased more than 50 times in comparison with that of non-addition specimen. On the other hand, the Seebeck coefficient decreased with the addition of Al2O3. This result suggests that the effect of the additives is very important to increase the value of power factor. The role of the addition of B4C, C and Al2O3 on the electrical conductivity and the Seebeck coefficients is discussed in this paper.