Effects of carbon and silicon on electrical, thermal, and mechanical properties of porous silicon carbide ceramics

The properties of porous SiC ceramics were investigated as a function of Si/C content. The addition of C to SiC decreased the electrical resistivity, thermal conductivity, and compressive strength of the porous SiC ceramics for an increase in C content from 0 to 50 wt%. In contrast, the addition of Si to SiC increased both electrical resistivity and compressive strength and decreased thermal conductivity for an increase in Si content from 0 to 30 wt%. The addition of 5 wt% C increased the electrical conductivity, compressive strength, and thermal conductivity of porous SiC ceramics because of the partial densification of SiC by the removal of silica via carbothermal reduction. The current results suggest that both the electrical and thermal conductivities of porous SiC ceramics can be adjusted in the range of 9.0 x 10(-2) -3.9 x 10(1) Omega cm and 1.3-31.4 W/(m.K), respectively, by controlling the Si or C content.