INTERFACIAL STRUCTURE AND TRANSVERSE-RUPTURE STRENGTH OF CEMENTED CARBIDES COATED WITH TITANIUM NITRIDE BY ION PLATING (PVD) PROCESS.

A titanium nitride layer was deposited mainly onto a HIP-treated WC-10%Co substrate at 773 K. The structure at an interface between substrate and layer and the transverse-rupture strength of the coated alloy were examined as a function of layer thickness and the surface state of the substrate (ground or polished). The effect of annealing on structure and strength was also examined. A foreign phase having no definite crystal structure formed generally at the interface. The thickness did not vary with the layer thickness but with the surface state of the substrate. The foreign phase changed to eta (Co//3W//3C) by annealing at 1073-1173 K. Rupture strength decreased with increasing thickness of the layer and with temperature.