Physical Properties of Diamond Coatings on a WC-6%Co Substrate

We have investigated the physical properties, including the morphology, texture, adhesion and chemical quality, of high-frequency chemical vapour deposited diamond coatings on WC-6%Co substrates, which were pre-treated by a two-step etching method. The results indicate that the increasing Co content from 0.12 to 3.05% within the etching depth of 5 µm caused a morphology transformation from prism diamond to spherulitic diamond, and a texture transformation from a {111} orientation to a {110} orientation. The Raman spectrum shows that the spherulitic diamond film contains more non-diamond phases (graphite, amorphous carbon and diamond-like carbon, etc) and has lower chemical quality than diamond films on a WC-6%Co substrate. The diamond coating grain sizes became about four times smaller when the deposition temperatures on the substrate surface were reduced from 1000 to 900°C. Compared with spherulitic diamond films, the prism diamond films exhibit better adhesion on the WC-6%Co substrate.