Influence of scratches on the wear behavior of DLC coatings

Abstract : In lubricated sliding contact systems with Diamond-Like Carbon (DLC) coated solids, several studies have shown that DLC coatings are highly sensitive to asperities breaking through the lubricant film within the contact area. Those asperities produce damages similar to those obtained from scratch tests from where coating delamination can initiate and propagate. In this work, the influence of initial surface degradations upon the coating lifetime is investigated using wear tests on initially scratched DLC coatings. Results shown that although scratches can be seen as initial damage leading to local spalling, they are likely to break the most prominent roughness peaks of the counterbody and, as a result, to protect the overall coated surface from excessive contact pressure and increase the overall coating lifetime.