A comparison of tribological and corrosion behavior of PVD-deposited CrN/CrAlN and CrCN/CrAlCN nanostructured coatings

The present study evaluates the tribological and corrosion behavior of CrN/CrAlN and CrCN/CrAlCN nanostructured coatings applied on 430 stainless steel. These coatings were applied using the physical vapor deposition method from the vapor phase through the cathodic arc technique. X-ray diffraction, field emission scanning electron microscopy, and nano-indentation techniques were utilized for the coatings characterization. Moreover, the adhesion of the coatings to the substrate was evaluated by the adhesion test according to the VDI3198 standard. The corrosion behavior of the coatings was studied by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 wt % NaCl solution in 24, 72, and 168 h. It was observed that CrN was the major phase in the coatings. The results of the Rockwell C test indicated the good adhesion of both coatings to the substrate. The hardness of CrCN/CrAlCN coating was 20 GPa and CrN/CrAlN coating was 18 GPa. Concerning the friction coefficient, 430 stainless steel, CrN/CrAlN, and CrCN/CrAlCN coatings showed friction coefficients of 1.049, 0.3, and 0.21, respectively. CrCN/CrAlCN exhibited the lowest friction coefficient, which can be ascribed to the higher ratio of H3/E2, higher hardness, and also reduced surface roughness compared to the CrN/CrAlN sample. The Rp value of CrCN/CrAlCN coating is higher than that of CrN/CrAlN coating at different times. The corrosion current density of the CrCN/CrAlCN coating was 0.003 μA cm−2 and for the CrN/CrAlN coating, it was 0.057. The obtained results from both corrosion tests are in an agreement and indicate the better resistance of the CrCN/CrAlCN coating against corrosion which can be due to the dense structure, lower roughness, and low wettability of this coating.