Mechanical Properties and Oxidation Resistance of Ti_1－XW_XN Coatings

抄録

Titanium-based hard coatings have been developed by adding different metals to TiN in order to obtain mechanical, tribological, and thermal properties that are superior to those of TiN. In this study, Ti_1－XW_XN films were synthesized from Ti_1－X-W_X alloy targets（X＝0, 0.25, 0.35, 0.5, 0.75, and 1.0）by radio-frequency magnetron sputtering. X-ray diffraction analysis indicated that all of the prepared films were solid solutions with a NaCl-type structure, and their interplanar spacing changed as the W content（X）was varied. The microhardness gradually increased from 21 GPa（at X＝0）to 28 GPa（at X＝0.66）and then decreased to 22 GPa（at X＝1.0）. The average coefficient of friction varied between 0.4 and 0.8, and the wear track had a depth below 0.15 μm in the films with X＝0-0.66. The exothermic peak of differential thermal analysis shifted from 814 ℃（at X＝0）to 846 ℃（at X＝0.34）during dynamic oxidation. Correspondingly, the film with X＝0.34 showed the smallest mass gain during isothermal oxidation at 600-700 ℃, and its resistance against oxidation was better than that exhibited by TiN（at X＝0）. The surface properties in terms of microstructure, microhardness, tribological properties, and oxidation resistance were also characterized as functions of the W content.