Compared the oxidation behavior of TiN and TiN/W2N ceramic coatings during heat treatment

TiN/W2N multilayer coatings with different modulation periods (modulation ratio was 1:1) changing from 2 nm to 7 nm were deposited by reactive magnetron sputtering. To evaluate the oxidation resistance of the multilayer coatings, heat treatment in the temperature range of 300-700 degrees C were conducted. The results showed that few oxides were formed on the surface of TiN and TiN/W2N multilayer coatings as the temperature below 500 degrees C. After heat treatment at 700 degrees C for 1 h, TiN coating was completely oxidized and TiN/W2N multilayer coatings still exhibited nitride phases. For TiN coating, the circular blister formed due to the generation of a biaxial compressive stress. On the contrary, for TiN/W2N multilayer coatings, the oxides presented in a form of particles due to the presence of layer-layer interfaces resulting in the grain sizes decreasing and the alternating stress forming. With the increase of the modulation period, the oxidation resistance of the multilayer coatings became worse due to the decrease of the layer-layer interfaces resulting in the inter-crystal gaps becoming larger and the alternating stress decreasing. TiN/W2N multilayer coatings exhibited a better oxidation resistance as compared to TiN.