Atomistic simulations of the load dependant friction force between silicon tip and diamond substrate

In this paper, the load dependence on the interfacial friction between a cubic silicon tip and diamond substrate was investigated using molecular dynamics simulations. With the increase of the applied load, the sliding process experiences the states of superlubricity, single slip instability, double slip instability and plastic stage. The transitions from one state to the next one occur at the contact pressure 5.3 GPa, 8.0 GPa and 10.8 GPa, sequentially. In the superlubricity state, both friction and dissipated energy approach zero, independent of the load. However, in the single slip state the friction has a linear relationship with load, while the double slip mode induces decreased frictional force and lower damping. The coupling of the structure and forces in the plastic regime leads to the reduction of friction. These behaviors show good agreement with the recent experimental observations and theoretical predictions.