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 °C in vacuum and at 600, 700, 800, and 900 °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 °C. A threshold temperature of 800 °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 °C improved mechanical and tribological characteristics of the films. The Ti–Cr–B–N and Ti–Al–Si–B–N films were more resistant against high-temperature oxidation than the Ti–B–N and Ti–Si–B–N films.