FRICTION MEASUREMENTS ON HOT-FILAMENT CVD DIAMOND FILMS DEPOSITED ON ETCHED TUNGSTEN CARBIDE SURFACES

Diamond-coated cemented carbides are a promising candidate for cutting tools, but a critical problem is the poor adhesion strength between the coating and the substrate. We have grown diamond films on WC-6%Co and WC-10%Co using hot filament CVD. Acid etching was necessary to remove Co from the substrate surfaces, and Co was more easily removed from the 10% Co sample. Scratch testing with a diamond stylus gave friction coefficients of 0.4-0.6. The standard deviation in the coefficient of friction during a pass was used as a measure of the adhesion quality when comparing films of similar morphology.