Influence of Oxygen Contents on the Microstructure, High Temperature Oxidation and Corrosion Resistance Properties of Cr–Si–O–N Coatings

Cr-Si-O-N coatings with different oxygen contents were deposited by multi-arc ion plating, where various O2/(N2 + O2) reactive gas rates were adopted. The XRD and XPS results showed that the CrN crystals disappeared with the increasing of the oxygen flux ratio to 10 at.%. The microhardness of all the Cr-Si-O-N coatings was approximately 2000 Hv0.05, which were dramatically plummeted compared to that of the Cr-Si-N coatings (≈3300 Hv0.05). The Cr-Si-O-N coatings were annealed under 800 °C and 1200 °C in the air atmosphere for 2 h to study the high-temperature oxidation resistance of the coatings. Meanwhile, Cr-Si-O-N coatings with different O2/(N2 + O2) rates were also used to carry out the corrosion resistance testing using the electrochemical working station in 3.5% NaCl solution under free air condition at room temperature. The results indicated that the coatings containing oxygen were more vulnerable to the high-temperature destruction and more easily corroded in the NaCl electrolyte.