Effects of solid solution, grain size and porosity on the thermal conductivity of aluminum- and boron-added porous silicon carbide ceramics with in-situ grain growth

Abstract

The effects of solid solution, grain size and porosity on the thermal conductivity of aluminum (Al)- and boron (B)-added porous SiC ceramics with in-situ grain growth were investigated. Al-added porous SiC ceramics showed higher porosity, higher solubility of Al in SiC lattice, and lower thermal conductivity with the range of 8.5 – 18.2 W/m⋅K. The higher solubility of Al in SiC lattice was considered as the reason of their low thermal conductivity. B-added porous SiC ceramics have lower porosity, lower solubility of B in SiC lattice, and higher thermal conductivity with the range of 30.6 – 79.0 W/m⋅K. The high thermal conductivity of B-added porous SiC ceramics would result from the low solubility of B in SiC lattice and the low porosity. The effect of grain size was found to increase the phonon mean free path for B-added SiC ceramics.