Silicon Carbide is among the hardest of ceramics, and retains hardness and strength at elevated temperatures, which translates into among the best wear resistance also. Additionally, SiC has a high thermal conductivity, especially in the CVD (chemical vapor deposition) grade, which aids in thermal shock resistance. It is also half the weight of steel.
Based on this combination of hardness, resistance to wear, heat and corrosion, SiC is often specified for seal faces and high performance pump parts.
Reaction Bonded SiC has the lowest cost production technique with a course grain. It provides somewhat lower hardness and use temperature, but higher thermal conductivity.
Direct Sintered SiC is better grade than Reaction Bonded and is commonly specified for high temperature work.
CVD SiC® is a face centered cubic, polycrystalline form produced by chemical vapor deposition. This material is extremely pure, and is specified for it’s excellent thermal conductivity approaching 300 W/mK. It is considerably more expensive to produce than the sintered or reaction bonded grades. ® Rohm & Haas.