The microstructure evolution of graphene in nanoindentation G/WC-Co based on molecular dynamics simulation

Abstract

In this paper, nanoindentation processes of graphene nanocoating reinforced cemented carbide (G/WC-Co) is simulated using molecular dynamics method, from which the effect of the relative position of the indenter and Co on the mechanical properties of G/WC-Co is investigated. Visualization techniques are employed to reveal the microstructure evolutionary behavior of graphene during the nanoindentation process. The results show that the loading force of cemented carbide with graphene nanocoating during nanoindentation is 18.2050 μN, which is 135.47 % higher compared to 7.7312 μN, the loading force of bare cemented carbide. At a nanoindentation of 8.3 Å, sp3 bond increases sharply in graphene, which results in the transformation of graphene into diamond-like carbon (DLC). The simulation results indicate that at the beginning of nanoindentation, the substrate exhibits significant loading resistance due to the high shear modulus of graphene itself. With the further development of nanoindentation, graphene ruptures, and part of graphene evolves to form DLC film, which enhances mechanical property of cemented carbide substrate.