Tribological behaviour of CVD diamond films on steel substrates

Diamond films have been prepared by microwave plasma chemical vapour deposition (MPCVD) on high-speed steel substrates pre-coated with an intermediate metal multi-layer system. Wear tests were performed in a micro-abrasion apparatus by a rotating ball, using a slurry of diamond abrasive particles in water (sphere-on-flat geometry). The tests were carried out on the bare steel substrate, on the substrate provided with the multi-layered system and, finally, on the diamond-coated samples. The worn surfaces were characterised by scanning electron microscopy (SEM) and micro-Raman spectroscopy, in order to identify the wear mechanisms involved. Wear data are compared and discussed. CVD diamond films have revealed an excellent performance for medium film thickness and moderate normal loads.