Nanofriction behaviors between silicon-doped diamond-like carbon films under different testing conditions

Abstract

Abstract Influence of Si contents on nanofriction behaviors between two Si-doped diamond-like carbon (Si-DLC) films is investigated via molecular dynamics simulation. The Si doping induces the friction of these films based on two reasons. The first reason is that the Si doping causes the formation of C-Si bonds in the films and decreases their internal friction, resulting in weak resistances for the relative sliding between them. The other is that the increase in Si content leads to an increase in the proportion of sp3-C atoms but makes them easier to transit to sp2 bonding states, raising the graphitization degree of the films. With high velocities and loads, the friction reductions of these films are also attributed to friction temperatures. A high friction temperature degrades the mechanical strength of the films and enhances their thermal expansions and their graphitization degree, leading to the easy-shear properties of friction interfaces.