PREPARATION, CHARACTERIZATION AND WEAR BEHAVIOR OF TINX-COATED CERMETS OBTAINED BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

Commercial cermet inserts were coated with titanium nitride by plasma- enhanced chemical vapour deposition (PECVD) using a pulsed direct curr ent (d.c.) glow discharge. The influence of the coating parameters on the deposition rate, on the layer composition, on the layer-substrate interface, on the structure and on the microhardness of the layers was investigated for deposition temperatures in the range 500-700 degrees C. The adhesive strengths, and some mechanical properties, of the coa ted cermets were characterized by scratch tests, by friction wear inve stigations and by measurement of the transverse rupture strength. The wear behaviour was examined in the cutting tests. It was found that Ti Nx-coatings deposited with a sufficiently high deposition rate and pla sma power density have a low oxygen and chlorine content and that they are nearly stoichiometric. The layers usually have a columnar structu re with a (200) texture. A granular, equiaxed structure was observed w ithin a small range of deposition conditions. In interrupted and conti nuous turning tests with steel and grey cast iron, a high cutting perf ormance of the coated inserts, which depended on the coating thickness and on the deposition temperature, was achieved.