High vacuum tribological performance of DLC-based solid–liquid lubricating coatings: Influence of atomic oxygen and ultraviolet irradiation

In this paper, the composition, structure, morphology and high vacuum tribological properties of three DLC-based solid–liquid lubricating coatings were investigated after atomic oxygen (AO) and ultraviolet (UV) irradiations. The research results showed that AO and UV irradiations induced the structural changes, including oxidation, bond breaking and crosslinking reactions of the DLC film and liquid lubricants, and the destruction of AO irradiation was much stronger than that of UV irradiation. After irradiations, the friction coefficient of the DLC-based solid–liquid lubricating coatings was lower than that before irradiation (except for AO irradiation), but the wear rates were larger due to irradiation destruction.