Atomic-scale understanding on the influence of sliding angle on the interfacial structure and friction behavior of textured amorphous carbon films

Abstract

Textured amorphous carbon (T:a-C) films have received great attention in the fields of hard drives, MEMS, and NEMS due to their excellent tribological properties. However, there is still a lack of research on the dependence of its friction behavior on different sliding angles. Especially, owing to the limitations of in-situ characterization in capturing the friction interface information, the potential friction mechanisms are still unclear. Hence, in this work T:a-C film with a rectangular shape was constructed and the impact of different sliding angles on friction behavior under dry friction condition was mainly explored through reactive molecular dynamics simulation. Results unveil that the friction properties of T:a-C films are closely dependent on the sliding angle. When the sliding angle increases from 0 degrees to 45 degrees , the decrease in the number of C - C covalent bonds at the friction interface weakens the interfacial crosslinking effect, leading to a decrease in the friction coefficient by 20.11 %. However, as the sliding angle further increases from 45 degrees to 90 degrees , an increase in friction coefficient is observed, which is due to the increase of unsaturated bond content, weakening the interface passivation effect. These results reveal the friction mechanism of T:a-C films, induced by sliding angle, and effectively guide the design and technical application of textured a -C films.