The influence of carbon content on the microstructure, mechanical and frictional property of chromium carbon nitride composite films

In this paper, a series of chromium carbon nitride (CrCN) composite films with various carbon content were deposited by changing the power of carbon target using RF-reactive magnetron sputtering system in the argon and nitrogen mixture gases. The microstructure, mechanical and frictional properties of CrCN films were investigated by X-ray diffraction (XRD), Raman spectrometer, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), nanoindentation and friction tester. According to the experimental results, the deposited binary CrN film exhibited a single face-centered cubic (fcc) structure, whereas the addition of carbon into the CrN matrix induced the formation of other phases of carbon and CNx. Both the solid solution strengthening and the increase of compressive residual stress improved the hardness from ~17 GPa at 0 at.% carbon to ~19 GPa at 6.3 at.% carbon. With the increase of C content, the friction curve of the CrCN film stabilized gradually and the average friction coefficient decreased gradually from 0.62 at 0 at.% carbon to 0.40 at 23.7 at.% carbon. The formation of lubricating amorphous carbon and CNx phase in the films mainly attributed to the improvement of friction property. •CrCN composite films exhibited a dual-phase of face-centered cubic Cr(C,N) solid solution and amorphous carbon.•Incorporation of carbon of 6.3 at.% into the matrix enhanced the hardness to ~19 GPa.•Incorporation of carbon significantly improved the frictional property.