Abstract
This study aimed to deposit Ti1-xZrxN coating with Zr/Ti+Zr ratio of 0.33, 0.50, and 0.67 on D2 steel by dc UBMS and investigate their oxidation behavior in the argon atmosphere using thermal Gravimetric analysis at different heat treatment temperature of 600, 700, 800, and 900oC. The heat treatment durations were all fixed in an hour. The oxidized layers were identified by XRD and XPS. The oxidized layers are Ti2ZrO6, TiZrO4, and TiZrO4 for Ti0.67Zr0.33N, Ti0.50Zr0.50N, and Ti0.33Zr0.67N thin film, respectively. The Ti2ZrO6, and TiZrO4 belongs to the (Ti, Zr) O2 system which is a srilankite structure. Ti0.67Zr0.33N thin films showed the worst thermal stability, and the Ti0.50Zr0.50N and Ti0.33Zr0.67N thin films showed a certain thermal stability at 600oC in argon atmosphere as showed in XRD patterns. The SEM images indicated intense volume expansion with increasing Zr/(Ti+Zr) ratio which caused worse morphology .The bubbles and macro cracks on the surface were detrimental for oxidation resistance. The heating temperature influenced the phase ratio of oxidized layers. The heating temperature range at 700 to 800oC was the best condition to form protective oxidized layer. The specimen Ti0.67Zr0.33N with TiO2 phase existed in the oxidized layer showed a minimal n value which implied TiO2 existed in oxidized layer was beneficial. The 700oC heat treated Ti0.67Zr0.33N thin films showed the best capability of oxidation resistance, since the smooth surface and TiO2 phase existed in oxidized layer were both beneficial to oxidation resistance. Results of the depth profile of oxidized layer revealed that the oxidation behaviors of TiZrN thin films were significantly influenced by their compositions. The growth of oxidized layer of Ti0.33Zr0.67N thin film was interface controlled .The growth of oxidized layer of Ti0.5Zr0.5N thin film could be attributed to mixed controls.