Effects of molybdenum-based substrate coatings on tribological performance of graphene films

Graphene is considered as a promising material for reducing friction and wear, owing to its structural features. The tribological properties of graphene depend on several factors, including thickness, fabrication process and substrate properties. However, the effect of substrate on the tribological behaviors of graphene films are not well known. Previous reports describe the nanoscale friction and wear behaviors of graphene films on different substrates, but the substrate effect-dependent macroscale tribological behaviors have not been demonstrated yet. In this work, the macroscale tribological performance of graphene films on different types of molybdenum (Mo)-based substrate coatings was investigated. It was found that the substrate coating hardness significantly influenced the tribological performance of graphene films as well as the formation of an effective lubricating transfer film. At a critical hardness value of the Mo-based substrate coating, the graphene film showed a low friction coefficient of ∼0.16 for 10,000 sliding cycles and a significant (∼16 × ) reduction in wear rate compared to that of the Mo single-layer coating without the graphene film. These findings aid in understanding the substrate-related tribological behaviors of graphene and thus widen its application in various industries.