Molecular Dynamics Simulation on Friction and Thermal Properties of FCC Copper in Nanoscale Sliding Contacts

In nanoscale sliding contact, adhesion effects and adhesive force are predominant, and high friction force will be produced. Friction energy is mainly converted into heat, and the heat will make nanomaterials become soft to affect friction behaviors, so it is important to investigate the friction and thermal properties of the nanoscale sliding contacts. A model of a nanoscale sliding contact between a rigid cylindrical tip and an FCC copper substrate is developed by molecular dynamics simulation. The thermal properties of the substrate and the friction behaviors are studied at different sliding velocities and different tip radii. The results show that at a low sliding velocity, the friction force fluctuation is mainly caused by material melting-solidification, while at a high sliding velocity the material melting is a main factor for the friction reduction. The average friction forces increase at initial phase and then decrease with increasing sliding velocity, and the average temperature of the substrate increases as sliding velocity increases. Increasing tip radius significantly increases the temperature, while the coupled effects of tip radius and temperature rise make friction force increase slightly.