The robust superlubricity behaviors of a-C:H films on different roughness interfaces at surface contact scale

Abstract

Hydrogenated amorphous carbon (a-C:H) film has demonstrated superlubricity in previous studies, but its effectiveness may be limited when applied to engineering components with surface contact and non-ideal smoothness. In this work, four kinds of plane contact friction pairs with different surface roughness (roughness of Sa from 21 nm to 544 nm) were designed and coated with a-C:H film with 43% hydrogen content by ionized beam deposition method. The results demonstrate that the film exhibits exceptional lubrication performance across various roughness interfaces, with the minimum friction coefficient reaching 0.005. The graphitization process and the actual contact state are discussed and calculated. These findings offer valuable insights into the potential application of highly-hydrogenated a-C:H film for moving parts in industrial equipment.