Effects of hydrogen on the physical and mechanical properties of carbide derived carbon

Carbide-derived carbon (CDC) is a form of carbon produced by reacting metal carbides, such as SiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the re-arrangement of the carbon atoms into an equilibrium graphitic structure. The structure of CDC is derivative of the original carbide structure and contains nanoscale porosity and both sp2 and sp3 bonded carbon in a variety of nanoscale structures. CDC can be produced as a thin film on hard carbides to improve their tribological performance. CDC coatings are distinguished by their low friction coefficients and high wear resistance in many important industrial environments and by their resistance to spallation and delamination. The tribology of the CDC can be affected by varying the conditions employed during the chlorination process. Varying the exposure time, temperature and chlorine concentration in the treatment gas can alter these properties. When hydrogen is introduced during treatment, or afterwards as a subsequent post-treatment, the properties of the CDC layer are modified, which further improves the tribological performance. These modifications help to reduce energy loss and result in a decrease in the rate of wear during sliding applications. The physical and mechanical properties of hydrogen enhanced CDC coatings on SiC surfaces are described in detail.