Tribological mechanism of diamond-like carbon films induced by Ti/Al co-doping

Co-doping two metals into diamond-like carbon (DLC) films exhibits a desirable combination of low residual stress and hard hardness for further application, but the insight into tribological mechanism induced by the co-doped metals is still not fully clarified yet. In this work, we fabricated the Ti/Al co-doped DLC films (Ti/Al-DLC) with various metal concentrations using the hybrid ion beam system, and the tribological properties of films were systematically investigated. Results revealed that the co-doped Ti/Al metals played an important role in the tribological behaviors of DLC films; the film deposited at 2.5 A (Ti10.06at.%Al4.78at.%) exhibited the lowest friction coefficient of about 0.05 and wear rate of 1.56 × 10−16 m3 N−1 m−1. This attributed to the formation of thick transfer layer in the friction interface, which could be described as a dual or hierarchy nanostructure constructed of cross-linking amorphous carbon networks and hard phase (mainly TiC and Al2O3) structures. [Display omitted] •Ti/Al co-doped diamond-like carbon films were fabricated by a hybrid ion beam method.•The tribological property strongly depended on the Ti/Al concentrations in the film.•The graphitization level on the wear tracks was observed for each case.•A transfer layer with cross-linked amorphous carbon and nanocrystalline was formed.•The transfer layer dominated the excellent tribological property of film at 2.5 A.