FACTORS AFFECTING GROWTH DEFECT FORMATION IN CATHODIC ARC EVAPORATED COATINGS

The origin of the conical features on the surfaces of are evaporated h ard compound coatings was investigated. A simple metallographic techni que was employed to show that these conical features are growth defect s made elf the coating material (TiN in our case) precipitated by macr oparticles of the cathode material, and not the macroparticles themsel ves. The effect of bias voltage characteristics, such as the amplitude (for d.c. voltage), frequency and duty cycle (for pulsed voltage), on the evolution of defects was also investigated. An increase in the am plitude or duty cycle resulted in a decrease in the defect density, R( a) and the surface area covered with the defects. A simple explanation for the phenomena observed is suggested.