Fretting friction and wear of polycrystalline diamond coatings

The tribological behaviour of diamond coatings deposited by widely different processes has been investigated. Hot-flame and microwave CVD diamond coatings show a homogeneous structure and morphology, whereas plasma jet diamond deposits display a laterally changing structure and morphology. The friction and wear behaviour of these three coating types sliding against a corundum counterbody showed a marked difference in a fretting test. A single-crystal diamond with a polished (100) surface was involved for comparative tests. An attempt is made to clarify the tribological behaviour of diamond coatings sliding against corundum in terms of the purity of diamond coating, its surface roughness and crystal orientation.