▎ 摘　　要

Graphene is a promising solid lubricant for diamond-based MEMS/NEMS devices to implement reliable and effective lubrication. While, few available studies focus on nanoscale friction behaviors of graphene on the diamond substrate and the underlying mechanism behind such lubricity remains unclear. Here, we demonstrated in a set of AFM tests that applying a layer of single layer graphene (SLG) onto the polycrystalline diamond substrate results in a reduction of the coefficient of friction by an order of magnitude and elimination of the anisotropy of friction coefficient. We elucidated the atomic mechanism behind such lubricity performance in systematical classical molecular dynamics simulations. It is found the friction of the SLG coated diamond surface is determined by the distribution of atomic forces acted on the atoms of the Si tip surface and positively correlated with the maximum value of these atomic forces. The atomic mechanism of the lubricity of graphene on the diamond substrate can be explained by the balanced atomic force distribution and reduced maximum atomic force on the mated tip with graphene on the sliding interface. We believe that the findings achieved in the present study would promote the application of graphene as a solid lubricant for diamond-based MEMS/NEMS devices.