Thermal and electrical properties in plasma-activation-sintered silicon carbide with rare-earth-oxide additives

This study investigates the thermal and electrical properties of SiC cerami cs with a combination of Y2O3 and rare-earth-oxide additions as sintering a dditives, by comparing four types of SiC starting powders varying in partic le size and chemical composition. The powder mixtures were plasma-activatio n sintered to full densities and then annealed at high temperatures for gra in growth. The thermal conductivity and electrical resistivity of the SiC c eramics were measured at room temperature by a laser-flash technique and a current-voltage method, respectively. The results indicate that the thermal conductivity and electrical resistivity of the SiC ceramics are dependent on the chemical composition and particle size of the starting powders. The thermal conductivities observed for all of the annealed materials with a ra re-earth La2O3 sintering additive were > 160 W-.(m(.)K)(-1), although low e lectrical resistivity was observed for all materials, in the range 3.4-450 Ohm (.)cm. High thermal conductivity, up to 242 W-.(m(.)K)(-1), was achieve d in an annealed material using a commercial 270 nm SiC starting powder.