Influence of Load on the Tribological Behavior of a-C Films: Experiment and Calculation Coupling

Although the tribological performances of various non-hydrogenated amorphous carbon films (a-C) have been investigated for decades, most of previous studies are reported with the experimental point, and the individual mechanism still lacks reasonable coupling of experimental and physical description. In this paper, influence of load on the tribological behaviors of a-C films was systemically investigated based on the correlation of tribological tests and physical calculations. Results shows that coefficient of friction (COF) and wear rate of a-C films both decreased with the increase of applied load during wear tests. It is observed that the coverage of easy-shear transfer film on the surface of counterpart almost keeps same for different applied load, indicating that the decreased COF is mainly attributed to the higher graphitization level. Besides, according to the energy dissipation theory, both the decreased COF and increased heat dissipation cause the decrease of the wear rate. Furthermore, with the increased applied load, entropy decreases and keeps well consistent with wear rate. All the analyzed curves based on the physical calculations possess high regression coefficient with the experimental data, which would deepen our understanding of the physical mechanism of a-C films with various contact pressure.