Microstructure and mechanical properties of the Cr–Mo–Si–N nanocomposite coatings prepared by a hybrid system of AIP and HiPIMS technologies

Abstract Quaternary Cr–Mo–Si–N coatings containing various Si contents were deposited on SUS304 and Si wafers by a hybrid coating system, where cathode arc ion plating (AIP) and high power impulse magnetron sputtering (HiPIMS) power sources were applied to the Cr and MoSi targets, respectively. The effects of Si content on the microstructure, surface roughness, mechanical and tribological properties of Cr–Mo–Si–N coatings were investigated. With increasing the Si content, both number and size of the macroparticles were decreased, leading to smoother coating surface, while the crystalline size was also decreased gradually. Strong (200) plane preferred orientation was confirmed in all coatings except for the sample with relatively high Si content i.e. 16.23 at. %, which existed mainly as amorphous phase. The microstructure evolution was changed from polycrystalline to nanocomposite structure and finally to an amorphous phase structure with increase of Si content. The hardness of Cr–Mo–Si–N coatings initially increased and then decreased with increasing the Si content due to the change of microstructure. The maximum hardness was approximately 26.1 GPa at Si content of 8.15 at. %, where nanocomposite Cr–Mo–Si–N coating was obtained containing nanocrystalline Cr(Mo)N phase and amorphous Si3N4 matrix. In these series of coatings, the average friction coefficient was decreased with Si addition and then rebound to nearly 0.46 when the Si content surpassed certain value. The tribological properties of the coatings were also examined and the best wear resistance performance was obtained at Si content of 8.15 at. %.