Studying the Diffusion-barrier Properties, Thermal Stability and Oxidation Resistance of TiAlSiCN, TiAlSiCN/AlOx, and TiAlSiCN/SiBCN Coatings

This paper studies the diffusion-barrier properties, resistance to thermal cycling, oxidation resistance, and thermal stability of TiAlSiCN single-layer coatings, as well as of TiAlSiCN/SiBCN and TiAlSiCN/AlOx multilayer coatings. The coatings were obtained by vacuum ion plasma technology combining magnetron and ion sputtering of TiAlSiCN, Si42B45C13, or Al2O3 ceramic targets with high energy ion implantation of growing coating by Ti2+ ions. The structure and properties of the coatings in initial state were analyzed by glow-discharge optical emission spectroscopy, high-resolution transmission electron microscopy, high-resolution scanning electron microscopy, energy dispersive spectroscopy, and nanoindentation. The high-temperature properties were estimated by isothermal and nonisothermal annealing, stepwise heating, and thermal cycling in air and in vacuum. It has been established that TiAlSiCN coating retains a specific nanocolumnar structure of nc-TiAlCN/a-SiCN and ultrahigh hardness of 37–49 GPa in the range of 20–1300°C, heat resistance up to 1000°C, and diffusion-barrier properties constrained by the temperature of 800°C. In comparison with the basic TiAlSiCN coating, the TiAlSiCN/SiBCN multilayer coatings are characterized by higher thermal stability up to 1400°C (TiAlSiCN/SiBCN), oxidation resistance up to 1100°C, resistance to diffusion of elements from substrate up to 1000°C, and resistance to thermal cycling at 1000°C (TiAlSiCN/SiBCN, TiAlSiCN/AlOx).