Tuning the electrical, thermal, and mechanical properties of porous SiC ceramics using metal carbides

The effect of addition of various metal carbides on the electrical, thermal, and mechanical properties of porous SiC ceramics was investigated. The results showed a decrease in the electrical resistivity from 1.2 x 102 to 1.3 x 10-3 omega center dot cm and thermal conductivity from 14.2 to 3.6 W.m- 1K-1 whereas the compressive strength increased from 12.7 to 21.1-81.1 MPa at -60.2% porosity. The decrease in electrical resistivity and thermal conductivity was caused by the introduction of conductive carbides and multiple heterophase interfaces, respectively, in the porous ceramics. The electrical and thermal conductivities and compressive strength of porous SiC-based ceramics, processed with a SiC-B4C-VC-ZrC-NbC composition, were 8.0 x 102 omega- 1 center dot cm- 1, 3.6 W center dot m- 1K-1, and 58.0 MPa, respectively. Therefore, it is proven that the electrical, thermal, and mechanical properties of porous SiC ceramics can be tuned over a wide range by adding a suitable combination of metal carbides.