Microstructure and Thermal Conductivity of Silicon Carbide with Yttria and Scandia

A fully dense SiC ceramic with high thermal conductivity was obtained by conventional hot pressing, with 1 vol% Y 2 O 3 – Sc 2 O 3 additives. The ceramic had a bimodal microstructure consisting of large and small equiaxed SiC grains. Observation with high‐resolution transmission electron microscopy ( HRTEM ) showed two kinds of homophase ( SiC / SiC ) boundaries, that is crystallized and clean boundaries, and a fully crystallized junction phase. The thermal conductivity of the SiC ceramic was 234 W (m·K) −1 at room temperature. The high thermal conductivity was attributed to a clean SiC lattice and good contiguity between SiC grains.