FORMATION OF CHROMIUM-COPPER COATINGS ON DIAMOND

The mechanism of chromium and chromium-copper formation is determined, which is mainly by transfer of metal ions to the reaction surface (of diamond) and carbon diffusion (from diamond) into the coating. Introd uction of copper oxides into the chromium metallizer promotes an incre ase in coating thickness due to the additional contribution to transfe r of chromium of CuO, Cu, and CrO. With reduction of copper oxides thi s contribution is reduced, which gives rise to a slower coating thickn ess growth rate. Slower growth is also caused by accumulation in the m etallizer of chromium oxides and carbides which block evaporation as w ell as inhibiting diffusion of carbon into the body of the coating.