Chemical Vapor Deposition (CVD)
Chemical Vapor Deposition (CVD) is a high temperature thermo chemical process operating at around 1000°C. In CVD processes the coating is deposited from a reactive gas atmosphere usually containing halogen chemical vapors. The chemicals used readily decompose at the high temperature in the reactor and recombine to form the desired coating on the hot parts. Corrosive by-products are also produced and these are removed from the coating vessel and neutralized in gas effluent scrubbers. The high temperature nature of CVD effectively restricts its use to parts which are not affected by the high temperatures used, e.g. sintered carbide. CVD can also be used to coat heat sensitive material, although in such cases, post-coat heat treatment is necessary to restore the properties of the substrate. Tools and components made from stainless steel and A,D, S and H series tool steels with loose tolerances are candidates for CVD coating.