Structure, Morphology, Thermal Stability and Oxidation Resistance of Multilayered TiSiN/VN Films: Influence of TiSiN-Layer Thickness

Abstract

In this paper, the influence of TiSiN layer thickness of TiSiN/VN multilayered films, deposited by DC reactive magnetron sputtering, on the structure, mechanical properties, thermal stability and, essentially, oxidation resistance is investigated. The films adhere well to the substrates and show a columnar structure growth, being the one with the highest TiSiN layer thickness the more compact. The as-deposited films exhibit fcc structure with broad diffraction peaks positioned between the TiN and VN standard peaks. Annealing at 800 °C for 2 h promotes structural changes in the films, i.e., single fcc diffraction peaks are subdivided into two diffraction contributions. The onset point of oxidation of the films is ~ 550 °C, independently of the thickness of the TiSiN layer. A strong diffusion of V to the top surface occurs for the film with the lowest TiSiN layer thickness. Thicker TiSiN layers offer a better barrier layer to the V diffusion due to the formation of a higher amount of protective oxides. The strong diffusion of V produces a plate-like V2O5 discontinuous layer on the top and a porous Ti-Si-V-O rich thick layer underneath.