The microstructure and phase evolution of cone-like VN coating in a wide temperature range

Abstract

Abstract The cone-like VN coatings were deposited on the surface of Si (100) substrate by RF magnetron reactive sputtering and their oxidation behavior was investigated in ambient air at temperatures ranging from 25 to 700 °C. The phase structure, surface morphologies and oxidation mechanism were studied using EPMA, SEM, XPS and TEM. The results reveal that there are three stages for the oxidation of cone-like VN coating. From 25 to 300 °C, the cone-like structure of VN coating has no change although a few cracks appeared due to the formation of V2O3 scales. The V2N phase could transform to V2O3 or VN phases. From 300 to 600 °C, the cracks start to expand and become more, meanwhile some grains start to grow and becomes irregular shape. The VN phase transforms to V2O3 and V2O5. Some formed V2O3 phase also transforms to V2O5. From 600 to 700 °C, the cone-like structure disappears although the grain boundaries are still apparent. The VN phase transforms to V2O5 and no V2O3 phase forms.