Hard coatings under vibrational contact conditions

Contacting surfaces subjected to small-amplitude oscillating motions ( fretting) can undergo severe damage. This paper is concerned with the investigation of a possible materials solution to this problem, i.e. the use of hard coatings. The different fretting modes and the relevant fretting variables and fretting regimes are explained in the Introduction. Then, selected results on the fretting of TiN, diamond-like carbon and diamond coatings are presented. The mechanical contact response is characterized with on-line analysis of the tangential force and the displacement. Ex situ characterization techniques are used to evaluate material modification in the contact. It is shown that the combined analysis of the mechanical contact response and the material modification in the contact allows us to quantify the damage and to understand the failure mechanisms of the coating material.