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

Hard TiN/SiN_x 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/SiN_x 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 SiN_x 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 SiN_x thickness, TiN/SiN_x multilayer coatings demonstrate excellent thermal stability and are potential candidates for high-temperature tribological applications.