TRIBOLOGICAL PROPERTIES OF SMOOTH POLYCRYSTALLINE DIAMOND FILMS

We have used a pin-on-disk tribometer with either a monocrystalline ru by or a 100Cr6 steel ball to evaluate the tribological properties of a series of polycrystalline chemical vapour deposition diamond films. D ifferent polishing treatments of the as-grown films resulted in marked differences of their tribological behaviour. The friction and wear of smooth nanocrystalline diamond films was dependent on the surface mor phology and roughness as well as the material transfer from the ball t o the film. Microcrystalline films polished by laser irradiation, thou gh being substantially rougher, showed a lower friction and minimal ba ll wear. Films polished by Ar-microwave plasma etching showed a simila r behaviour as the laser-irradiated samples. However, the him with rou ghness comparable with the laser polished samples produced significant ly higher ball wear. An unrivalled tribological performance was obtain ed with mechanically polished diamond films.