Predominant role of fatigue crack evolution and tribo-chemistry on tribological behavior of Si-DLC film under different relative humidity.

With coupled mechanical-chemical field, the predominant role of fatigue crack evolution and tribo-chemistry on Si-DLC films were investigated under different relative humidity. Results show that incorporating Si stabilized friction interface and induced lubricating carbonaceous material transfer (0.053 under 20% RH), but the lubricating effect was deteriorated (0.12) by the iron oxide products on sliding shear stress. Furthermore, Si element aggravate overall wear rates than DLC film. Increasing relative humidity was beneficial to lowering wear rates of films with lower Si content, but aggravated the wear rates of films with higher Si content. The predominant role of tribo-chemistry on the friction coefficient (COF) was confirmed, meanwhile, critical impact of fatigue cracks evolution on surface wear is worse than that of tribo-chemistry. • Incorporating Si induced lubricating carbonaceous transfer, but the iron oxide products deteriorated lubricating effect. • Increasing relative humidity reduced wear rates of lower Si films, but aggravated the wear rates of higher Si films. • The fatigue cracks evolution of Si-DLC films was consistent with the increasing wear rates of Si-DLC films. [ABSTRACT FROM AUTHOR]