Effect of carbon content on electrical, thermal, and mechanical properties of porous SiC ceramics with B4C and C additives

Abstract

The electrical, thermal, and mechanical properties of porous SiC ceramics with B4C-C additives were investigated as functions of C content and sintering temperature. The electrical resistivity of porous SiC ceramics decreased with increases in C content and sintering temperature. A minimal electrical resistivity of 4.6 × 10−2 Ω·cm was obtained in porous SiC ceramics with 1 wt% B4C and 10 wt% C. The thermal conductivity and flexural strength increased with increasing sintering temperature and showed maxima at 4 wt% C addition when sintered at 2000 °C and 2100 °C. The thermal conductivity and flexural strength of porous SiC ceramics can be tuned independently from the porosity by controlling C content and sintering temperature. Typical electrical resistivity, thermal conductivity, and flexural strength of porous SiC ceramics with 1 wt% B4C-4 wt% C sintered at 2100 °C were 1.3 × 10−1 Ω·cm, 76.0 W/(m·K), and 110.3 MPa, respectively.