Thermal and electrical properties of additive-free rapidly hot-pressed SiC ceramics

Abstract

The thermal and electrical properties of newly developed additive free SiC ceramics processed at a temperature as low as 1850 °C (RHP0) and SiC ceramics with 0.79 vol.% Y2O3-Sc2O3 additives (RHP79) were investigated and compared with those of the chemically vapor-deposited SiC (CVD-SiC) reference material. The additive free RHP0 showed a very high thermal conductivity, as high as 164 Wm−1 K−1, and a low electrical resistivity of 1.2 × 10−1 Ω cm at room temperature (RT), which are the highest thermal conductivity and the lowest electrical resistivity yet seen in sintered SiC ceramics processed at ≤1900 °C. The thermal conductivity and electrical resistivity values of RHP79 were 117 Wm−1 K−1 and 9.5 × 10−2 Ω cm, respectively. The thermal and electrical conductivities of CVD-SiC parallel to the direction of growth were ∼324 Wm−1 K−1 and ∼5 × 10−4Ω−1 cm−1 at RT, respectively.