Transition in Microstructure, Mechanical and Oxidational Properties Induced by Phase Transformation of Zr_1－XAl_XN

抄録

In this study, we evaluated the microstructure, microhardness, tribological properties, and oxidation behaviors of Zr_1－XAl_XN films, considering the requirements for their use as wear-resistant coatings. Zr_1－XAl_XN films were synthesized by radio-frequency magnetron sputtering from （ZrN）_1－X-Al_X targets. X-ray diffraction analysis indicated that the Zr_1－XAl_XN film had a cubic phase when X＝0.12, being transformed into a mixture of cubic and hexagonal phases when X＝0.26. Zr_0.88Al_0.12N displayed an average frictional coefficient of 0.3-0.5 and a minimum wear depth of 0.4 μm. The microhardness of Zr_1－XAl_XN decreased from 36.5 GPa for X＝0.12 to 16.9 GPa for X＝0.43. During dynamic oxidation, the exothermic peak in a differential thermal analysis curve shifted from 730 ℃ for X＝0.12 to 835 ℃ for X＝0.43. In accord with this behavior, the mass gain measured by thermogravimetric analysis for Zr_0.57Al_0.43N exhibited minimum values at isothermal oxidation temperatures in the range of 600-700 ℃.