High temperature tribology behavior of silicon and nitrogen doped hydrogenated diamond-like carbon (DLC) coatings

To improve the thermal stability and mechanical performances of the DLC coating at high temperature, thermodynamically stable Si-N and C-N bonds were introduced into the DLC coating by co-doping Si and N elements. The friction coefficient and wear rate changed from 0.055 and 1.93 × 10 −7 mm 3 /Nm (25 °C) to 0.033 and 7.3 × 10 −6 mm 3 /Nm (500 °C). The superior tribological performances of Si, N-DLC coating at 500 °C was attributed to the formation of compacted layers with high hardness (9.2 GPa) and elastic recovery (~89%) on the wear track during running-in period. The compacted layer possessed a high compliance and large deformation capacity due to the fullerene-like nanostructure within amorphous carbon network and the shear-induced stacked structure, thereby reducing the friction.