Improving thermal stability of TiSiN nanocomposite coatings by multilayered epitaxial growth

Owing to the superior mechanical properties, nanoscale multilayer coatings are regarded as excellent protective layers for machining applications. Here, the effect of multilayer architecture on the structure and thermal stability of TiSiN nanocomposite coating is investigated. Corresponding to the TiSiN nanocomposite coating with nanocrystalline grains encapsulated by the amorphous matrix, TiSiN/TiN coating, consisting of 6.6 nm TiN and 3.7 nm TiSiN layers, exhibits the epitaxial growth with coherent interfaces and thus results in a complete Si-solution of TiSiN sublayers. The coherency strains in multilayer retard the thermal decomposition behavior of TiSiN sublayers. Therefore, the hardness of TiSiN/TiN multilayer can be maintained at ~ 38.9 GPa upon annealing to 1100 °C, where the hardness of TiSiN coating already decreases from as-deposited ~ 40.6 GPa to ~ 36.2 GPa due to the grain coarsening and the thermal decomposition.