The oxidation resistance and mechanical properties of MoNx/AlN multilayer gradient films prepared by magnetron sputtering

Abstract

In order to investigate the properties of MoNx/AlN multilayer gradient films, MoNx/AlN gradient films with 4, 8, 12, 16 and 20 gradient layers were prepared by double-target co-sputtering. The phase structure, morphology, and element composition of films before and after oxidation were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and energy dispersive spectrometer (EDS). The mechanical properties of films were characterized by nanoindenter. The results indicate that the MoNx/AlN multilayer gradient films are composed of face-centered cubic Mo2N and hexagonal AlN. With increasing the number of gradient layers, and the columnar structure of films gradually becomes uniform and dense. The average grain size of MoNx in gradient films decreases first, then increases slightly and finally decreases. The oxidation resistance of gradient films is better than that of pure MoNx film. And with increasing the number of gradient layers, the oxidation resistance of MoNx/AlN gradient films is gradually enhanced. The hardness of MoNx/AlN gradient films first decreases from 23.68 ± 1.18 GPa of 4-layer film to 16.68 ± 0.83 GPa of 12-layer film and then increases to 21.12 ± 1.06 GPa of 20-layer film.