Shear-induced interfacial reconfiguration governing superlubricity of MoS2-Ag film enabled by diamond-like carbon

Robust superlubricity of the disulphide-based film or diamond-like carbon (DLC) coating has been systematically investigated in relation to interfacial nanostructures and environmental atmospheres. Nevertheless, the frictional performances of the tribo-couple between them, especially the underlying mechanisms governing superlubricity are scarcely touched. In this study, we designed the periodically multilayered MoS2-Ag film based on ion beam assisted deposition (IBAD) and found a superior lubricating durability of the film with a superlow friction coefficient of 0.0065 triggered by DLC film under a load of 10 N in N2. The in-depth structural analysis on the contact areas of tribopairs were performed through Raman and high-resolution transmission electron microscopy (HRTEM). The results demonstrate that sliding-affected regions of the film generally undergo a deep amorphization transformation and the materials are transferred to counterfacing ball to form a multiphase tribofilm. The prevailing mechanisms emphasize that the superlubricious status highly depends on the synergistic effect from both the physicochemical properties of shear-induced tribofilm and the structural transformation of the MoS2-Ag surface by different contact mechanics and reconfiguration pathways. The findings shed light on the nature of tribochemical mechanisms of MoS2-Ag film and provide a new strategy to achieve macroscale superlubricity of the disulphide-related lubricants.