The Interior Failure of Single‐Layer Graphene Activated by the Nanosized Asperity on the Substrate Surface

Abstract The influence of the nanosized asperity on the wear resistance of the single‐layer graphene (SLG) is investigated by an atomic force microscope. For the SLG on the polished diamond substrate, a 15 nm high asperity underneath it can cause a significant reduction of the critical contact pressure initializing the failure in its interior region from 43.75 to 8.31 GPa (calculated by the Derjaguin–Muller–Toporov model). The SLG fails at the inclined surface with a larger inclination angle around the bump region at first due to the increased shearing strength and the introduced lattice strain. Then, the fracture of graphene occurs at the newly formed step edges and rapidly propagates along the scanning path, which finally results in a complete failure of the SLG. The findings in this study reveal that the surface asperity on the substrate may be one of the factors that lead to the sharp discrepancy between the nanoscopically ultrastrong strength and the macroscopically weak wear resistance of graphene.