The depth profile analysis of W-Si-N coatings after thermal annealing

The aim of this research was to examine in detail the effect of the thermal annealing process with temperatures up to 1200 °C on W-Si-N amorphous films deposited onto refractory steel substrates. Particular attention was paid to the analysis of the chemical composition and the mechanical properties through the coating thickness. The results obtained indicate that the crystallisation process leads to an increase in the hardness of the coating, while for annealing temperatures higher than 1000 °C a decrease was observed. Up to 1000 °C, no significant changes in properties were detected across the thickness of W-Si-N films. However, for higher annealing temperatures, particularly at 1200 °C, an important loss of nitrogen was detected at the surface layer, accompanied by elemental inter-diffusion between the substrate and the coating. As a consequence, a thin layer was formed at the interface, composed of a mixture of phases integrating elements from both the film and the substrate