CVD-WC and WC _xN_y diffusion barrier coatings on WC/Co metalloceramics

Conventional hard metal coatings on WC/Co metalloceramics are treated at elevated temperatures by cobalt diffusion. That could prevent applying suitable barrier sublayers. The paper presents results on the possibility tungsten carbide (WC) and carbonitrides (WC _xN_y) CVD layers to be used as a barrier against Co diffusion. The coatings were prepared using two CVD methods: direct growing of WC or WC _xN_y and carborization/carbonitridization of W films. The level of diffused Co was investigated by X-ray microprobe technics, Auger electron spectrometry and direct layer by layer spectral analysis in the hollow cathode glow discharge method. Results show that WC and WC _xN_y coatings are prospective for preventing diffusion interaction between the substrate and the functional coatings.