The Effect of Cr Content on the Oxidation Behavior of Ti-Cr-N Films

Coatings

James E. Krzanowski¹ 

[1] Materials Science Program, University of New Hampshire, Durham, NH 03824, USA; E-Mail:

关键词: oxidation;    nitrides;    X-ray photoelectron spectroscopy;    X-ray diffraction;   

DOI  :  10.3390/coatings4020308

来源: mdpi

【 摘 要 】

Ti_1−xCr_xN thin-film samples were sputter-deposited with lateral composition gradients x = 0.1–0.9 across each sample. In order to determine the effect of Cr content on oxidation, samples were air-oxidized at temperatures ranging from 650 to 950 °C. The extent and type of oxide formed was characterized using X-ray diffraction. Only minor oxidation was observed for the 650–750 °C temperature range. At 850 °C, films below x = 0.7 showed poor oxidation resistance, with the formation of TiO₂ and Cr₂O₃ oxides, but little oxidation occurred above x = 0.7. At 950 °C, films above x = 0.7 again exhibited the best oxidation resistance. Chromium nitride films, which deposited as Cr₂N, were found to begin oxidizing at 750 °C, indicating that the increased oxidation resistance of the higher-Cr Ti-Cr-N films can be attributed to the Ti-induced stabilization of the B1-structured phase. A compositionally-uniform film (x = 0.79) was also deposited and analyzed by XPS before and after oxidation. Oxidation resulted in primarily Cr₂O₃ at the surface, with some TiO₂ also present, with the oxide richer in Cr than the starting film composition. These results suggested that at higher Cr compositions in the film, the oxidation mechanism was controlled by Cr diffusion to the surface.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.