Preparation and tribological characterization of amorphous carbon nitride coatings in a RF PECVD-DC PVD hybrid coating process

► CNx coatings were successfully prepared using a hybrid coating process with the combination of RF PECVD and DC magnetron co-sputtering of graphite target at different N2/Ar flow ratios. ► The structural properties of CNx coating were greatly affected by the N2/Ar flow ratio. ► Friction coefficients of CNx coatings in air and N2 gas stream showed less dependency on the N2/Ar flow ratio. ► The friction behaviors of CNx coatings are mainly controlled by the tribo-films on the mating surfaces.