AbstractThis study discusses CrAlSiN coatings obtained by vacuum arc plasma deposition. The structural and compositional parameters that are responsible for the most essential coating properties are identified. The structural morphology, elemental distribution, and phase composition of the coatings are investigated. The physicomechanical, adhesive and tribological characteristics are determined. Coatings were deposited on substrates of nitrided and carburized structural steels widely used in mechanical engineering. The coating properties are determined and compared with the corresponding surface properties of the standard uncoated specimen. The coating thickness for the experimental specimens was 0.82–1.18 µm. A comparative analysis of the coating phase composition is carried out using X-ray photoelectron spectroscopy (XPS) and thermodynamic calculations with Termo-Calc software. It is shown and proved experimentally that ion plasma coatings are nonequilibrium. In addition, CrAlSiN coatings significantly increase the mechanical characteristics of the material, such as hardness and resistance to elastic and plastic deformation, and adhere well to the substrate surface. In tribological tests, CrAlSiN coatings reduce the wear rate by a factor of 2–4 compared to nitrided steel and by an order of magnitude compared to carburized steel. These high properties are also attributed to the nonequilibrium structural-phase state of the coating. The obtained results indicate that vacuum arc plasma CrAlSiN coatings can be used as wear resistant protective coatings, including under friction conditions."