High temperature oxidation behavior of Ti0.5Al0.5N coating and Ti0.5Al0.4Si0.1N coating

Good oxidation resistance of hard coatings is important for cutting tools. Ti0.5Al0.5N coating and Ti0.5Al0.4Si0.1N coating were deposited by cathodic arc evaporation and their oxidation behavior at 850 °C, 900 °C and 1000 °C was compared. The effect of Si addition on the oxidation resistance of Ti0.5Al0.4Si0.1N was investigated. Results show that the oxidation resistance of Ti0.5Al0.4Si0.1N coating at 850–1000 °C is superior to Ti0.5Al0.5N coating. The improved oxidation resistance of Ti0.5Al0.4Si0.1N coating can be ascribed to the combined action of Al2O3 and SiO2 barrier layer, the reduction of columnar structure and the refinement of grains. In particular, Si addition increases the diffusion coefficient of Al and promotes the preferential formation of Al2O3 barrier layer. ▸ The oxidation resistance of Ti0.5Al0.4Si0.1N coating at 850–1000 °C is superior to Ti0.5Al0.5N coating. ▸ Si addition increases the diffusion coefficient of Al. ▸ Si addition promotes the formation of Al2O3 and SiO2 barrier layer. ▸ Si addition stimulates the reduction of columnar structure and the refinement of grains.