Status and perspective on mechanical and protective properties of PVD MeSiN nitride nanocomposite coatings

MeSiN nanocomposite coatings have attracted growing interest due to their exceptional combination of high hardness, wear, and corrosion resistance. However, existing studies still lack a comprehensive analysis of their microstructural characteristics, performance metrics, and optimization strategies. This review critically examines recent advances in the fabrication techniques, structure–property relationships, and potential optimization strategies of MeSiN coatings. Depending on the silicon content, MeSiN systems exhibit three structural regimes: solid solution, nanocomposite, and amorphous structure. Among them, the nanocomposite configuration, comprising nanocrystalline MeN grains embedded within an amorphous SiN x matrix, offers the most balanced improvement in mechanical strength and environmental resistance (hardness 20 ~ 40 GPa, oxidation temperature 900 ~ 1000 °C). The effects of Si and the Si-based coating structure in mechanical strengthening as well as corrosion and oxidation protection are discussed in detail. Furthermore, optimization perspectives are proposed. Multicomponent coating and multilayer architecture collectively enhance thermal stability, mechanical strengthening, and corrosion performance. Remaining challenges include limited understanding of degradation mechanisms under complex service conditions, the need for improved interface engineering, and the implementation of data-driven design strategies. This study offers insights into the development of next-generation MeSiN coatings for extreme environments in aerospace, marine, and manufacturing applications.