Thermal stability of hard TiN/SiNx multilayer coatings with an equiaxed microstructure

Hard TiN/SiNx multilayer coatings with an equiaxed microstructure were prepared using a dual-cathode unbalanced reactive-magnetron sputtering system. These multilayer coatings were then annealed at 1000 °C for 1 h in vacuum. These TiN/SiNx multilayer coatings before and after annealing were characterized at room temperature and compared in terms of microstructure and mechanical properties. X-Ray diffraction and cross-sectional transmission electron microscopy studies showed that the layer structure of these coatings is preserved after annealing at 1000 °C when the SiNx layer thickness is 0.8 nm or greater. The high hardness of these multilayer coatings is either maintained or improved after annealing. Therefore, with proper control of the SiNx thickness, TiN/SiNx multilayer coatings demonstrate excellent thermal stability and are potential candidates for high-temperature tribological applications.