A study of the oxidation behavior of multilayered tungsten nitride/amorphous tungsten oxide film prepared in a planar magnetron sputtering system

Tungsten nitride and tungsten nitride/amorphous tungsten oxide multilayered films were produced by a planar type reactive sputtering system on glass and stainless steel substrates. The effect of amorphous tungsten oxide top layer on oxidation behavior of tungsten nitride film has been characterized by thermal analysis using TGA and DTA. The structure of the film at different thermal-annealing temperatures was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties of the films at different heat-annealing states were measured by nano-indentation. It was found that the tungsten nitride film oxidized in air at 600 °C by the dissociation of face center cubic (fcc)–W2N to WO3 and WO2.92 and showed low hardness of 6 GPa. The addition of 500 nm thick amorphous tungsten oxide top layer to tungsten nitride film can further improve the oxidation resistance. Multilayered film oxidized in air at 800 °C by the dissociation of face center cubic (fcc)–W2N to WO3 and WO2.92. The film retained a hardness of 24 GPa after annealing at 600 °C for 10 h. This indicates that this film is a good candidate for high temperature applications.