WEAR TESTING OF CVD DIAMOND FILMS

A variety of diamond films with varying thicknesses from 40 to 1200 nm have been prepared by microwave plasma chemical vapour deposition (CVD). Their wear performance has been investigated as a function of morphology and layer thickness along with their surface roughness and Raman features. Accelerated wear testing was performed with a modified sphere-on-tape test using lapping tapes of differing abrasiveness. The wear data of the thin film deposits are compared with data obtained for bulk WC, AlN, Si, Al2O3 and other materials. The CVD diamond films are shown to be much more wear resistant than other well-established low wear materials, almost independent of morphology and layer thickness. Layers with an RMS roughness above 20 nm are shown to damage the abrading tapes severely. Ultralow wear, smooth CVD diamond coatings, down to thicknesses of 40 nm, are shown to be feasible.