INVESTIGATION OF COBALT BEHAVIOR DURING DIAMOND DEPOSITION ON CEMENTED CARBIDES

Obtaining high quality diamond depositions on cemented carbides is hin dered by the presence of cobalt. This study deals with the movement of cobalt and its interaction with diamond crystals. The deposition was carried out using a hot-filament chemical vapour deposition method and a CH4-H-2 1% gas mixture. Diamond-ground cemented carbide substrates (WC-6%Co) were used. The diamond coatings were investigated by transmi ssion electron microscopy, scanning electron microscopy, Auger electro n spectroscopy and Raman spectroscopy. It was found that the interacti on between diamond and cobalt results in zones which contain small cob alt particles and disordered graphite. The disordered graphite obtaine d as a result of the presence of cobalt promotes nucleation of diamond .