Wear and Corrosion Resistance of CrN Films on Oxynitriding-treated Vanadis 8 Tool Steel via the DC Magnetron Sputtering Process

Abstract

This research coated CrN films on oxynitriding-treated Vanadis 8 tool steel using the DC magnetron sputtering process of the PVD technique. The experimental parameters include different gas flow rates (Ar/N₂ was 20/20, 24/16, 28/12, and 32/8, respectively), with a bias of -50 V, power of 100 W, deposition temperature of 300°C, and deposition time of 180 min, respectively. The experimental results show that Vanadis 8 tool steel can form an effective oxynitriding layer with a depth of about 50 µm after the oxynitriding treatment, and the surface hardness increased to about 1400 HV0.05. Furthermore, the duplex coating layers exhibited optimal properties when the CrN films treated at an appropriate gas flow rate of Ar/N₂ was 24/16. Meanwhile, according to XRD analysis, the coating layer has a relatively high content of CrN composition, as well as the best wear resistance (the lowest specific wear rate when the loads of 2 N and 4 N were 2.05 × 10^-5 and 1.56 × 10^-5 mm³·m^-1·N^-1) and good corrosion resistance (in a 3.5 wt% NaCl environment, I_corr = 3.05 × 10^-4 A·cm^-2, R_p = 362.52 Ω·cm²). Overall, this study reveals that the CrN/oxynitriding duplex surface treatment could effectively improve the wear and corrosion properties of Vanadis 8 tool steel.