Thermal stability and oxidation resistance of Ti-B-N, Ti-Cr-B-N, Ti-Si-B-N and Ti-Al-Si-B-N films

Films Ti-B-xN-y(Al,Si,Cr) with different compositions x=25-33 at.% and y= 11-14 at.% were deposited by DC magnetron sputtering of TiBN, TiCrB, TiSiB, and TiAlSiB composite targets in a gaseous mixture of argon and nitrogen. The structure and phase composition of films were studied by means of X-ray diffraction, transmission electron microscopy, Raman and X-ray photoelectron spectroscopy. To evaluate the thermal stability and oxidation resistance, the Ti-B-N, Ti-Cr-B-N, Ti-Si-B-N, and Ti-Al-Si-B-N films were annealed at 600, 800, and 1000 degrees C in vacuum and at 600, 700, 800, and 900 degrees C in air, respectively. The elemental depth profiles for the oxidized films were obtained by focused ion beam equipped with secondary ion mass spectrometer. The Ti-B-N and Ti-Cr-B-N films demonstrated thermal stability up to 1000 degrees C. A threshold temperature of 800 degrees C was determined, below which these films acted as a diffusion barrier for Ni diffusion from metallic substrate. Annealing in the range of 600-800 degrees C improved mechanical and tribological characteristics of the films. The Ti-Cr-B-N and Ti-AlSi-B-N films were more resistant against high-temperature oxidation than the Ti-B-N and Ti-Si-B-N films. (c) 2006 Elsevier B.V. All rights reserved.