In pump seals, faces of hard material, such as SiC slide past one another. To avoid friction losses and leakage, the surfaces must have low friction coefficients and minimal wear. While SiC has excellent wear resistance, its friction coefficient in dry sliding wear is substantial. Treatment of the SiC surface in chlorine containing gases at elevated temperature, removes silicon as a volatile chloride, converting a layer of SiC to carbon with a unique structure consisting of nanocrystalline diamond, graphite, nano-onions and amorphous carbon.. This Carbide Derived Carbon (CDC) has a low friction coefficient, hardness greater than graphite, and excellent adhesion to the underlying ceramic. Use of CDC coatings on SiC surfaces in pump seal faces and other friction sensitive applications has the potential to reduce friction losses and maintenance requirements for equipment. The tribological properties of CDC on SiC and modification in the CDC process to improve performance under conditions relevant to pump seal and bearing service are discussed.