PREPARATION, CHARACTERIZATION AND WEAR BEHAVIOR OF PACVD CERMETS

Commercial cermet inserts were coated with TiNx, TiCxNy and (Ti, Si)N- x by plasma-assisted chemical vapour deposition using a pulsed d.c, gl ow discharge. The influence of the coating parameters on the depositio n rate, layer composition, layer-substrate interface, structure and mi crohardness of the layers was investigated within the deposition tempe ratures of 773-973 K. With optimized process parameters, layers with a low oxygen and chlorine impurity, high microhardness and a good adhes ive strength are obtained. Higher microhardness values compared with t hat of TiNx were observed for TiCxNy and (Ti, Si)N-x layers depending on the layer composition. Usually, the TiNx and also the TiCxNy and (T i, Si)N-x layers with low carbon and silicon contents have a columnar structure with a (200) texture. The structure changes with rising carb on and silicon concentrations. The edge life of the insert tips is mar kedly increased for cast iron and steel machining.