Effect of titanium carbide addition on the thermoelectric properties of B4C ceramics

TiB2/B4C composite ceramics are prepared via hot pressing, in which the TiB 2 particles are formed by introducing TiC0.78 and through the reaction betw een B4C and TiC0.78. The electrical and thermal conductivities and Seebeck coefficient of samples containing 0, 12.5 and 25.4 vol% TiB2 are measured f rom room temperature up to 1200 K. The results show that the transport prop erties of the samples vary with the TiB2 content. The transport properties of a 12.5 vol% TiB2/B4C sample are dominated by the B4C matrix as in undope d B4C ceramics, whilst the transport properties of a 25.4 vol% TiB2/B4C sam ple an dominated by TiB2 particles. The figure of merit of the 25.4 vol% Ti B2/B4C sample is higher than that of the undoped B4C ceramic sample between room temperature and about 700 K, which indicates that it is possible to i mprove the thermoelectric properties by selecting an optimum combination of different materials. (C) 2000 Elsevier Science Ltd. All rights reserved.