Insights on low-friction mechanism of amorphous carbon films from reactive molecular dynamics study

Abstract

The dependence of friction behaviors of the self-mated a-C system on sliding velocity, v, and contact pressure, P, was investigated systematically by reactive molecular dynamics simulation. Results demonstrated that the friction coefficient and sp(3)-to-sp(2) transformation of interfacial structure were more sensitive to the contact pressure than the sliding velocity. By analyzing the relation of friction coefficient and interfacial hybridization structure with P/v ratio, it suggested that the low friction coefficient, which was accompanied by the low sp(2) fraction, was strongly dependent on the passivation of friction interface as the primary mechanism. These findings disclose the proof for passivation mechanism mentioned in previous experiments, and also provide the potential strategy to fabricate new nanocomposite a-C films by surface/interface modification for tribo-applications.