Effect of multicomponent doping on the structure and tribological properties of VN-based coatings

Abstract The VN-based coatings doped with different elements (carbon, aluminum and silver) were comprehensively investigated in terms of their chemical composition, structure, mechanical properties as well as tribological performance. Results revealed that introduction of aluminum into the coatings can enhance the hardness and modulus of coatings resulting from solution strengthening of Al and the formation of hard AlN phase. The sp2-hybrized carbon and VC phases were found in C-doped coatings, playing decisive roles in reducing the friction at room temperature and raising hardness of coatings, respectively. The addition of silver significantly changed the mechanical and high temperature tribological behavior of the coatings owing to their easy-shearing structure. All coatings had the lower friction coefficients at 550 °C than those at room temperature. Among them, the friction coefficient of VAlCN–Ag coating is as low as about 0.25 at 550 °C, which is closely related to the synergistic lubrication dominated by V2O5 and silver vanadate phases formed by tribochemical reaction on the worn surface, indicating a design of promising self-lubricating VN-based coatings working at high temperature.