Corrosion behavior of CrN_x coatings deposited by hot target reactive magnetron sputtering

Hot Cr target magnetron sputtering with radio-frequency inductively-coupled plasma (RF-ICP) source and separate gas (Ar+N₂) inlets were used to obtain CrN_x coatings. Higher deposition rates (137 nm/min) can be obtained using hot Cr target due to its sublimation at elevated temperatures in comparison with conventional reactive magnetron sputtering (10-50 nm/min). While the separated gas (Ar, N₂) inlets and RF-ICP assistance were applied to improve stability and decrease hysteresis effects of deposition process. The corrosion behavior of the CrN_x coatings was investigated by potentiodynamic method in a 3.5wt% NaCl solution in the range from -800 to 800 mV with a sweep rate of 0.5 mV/s. Results of the tests have shown the role of deposition parameters on corrosion resistance of the coatings. Pure chromium and CrN coatings had the lowest corrosion rate in 3.5wt% NaCl solution, when the substrate bias potential was equal to -100 V. Under these deposition conditions, the coatings had higher hardness (11.2 and 21.3 GPa for Cr and CrN) and denser columnar microstructure in comparison with the coatings obtained at lower bias potential. The reported study was funded by RFBR according to the research project № 20-38-90134.