Uniform design method for optimization of process parameters of plasma sprayed TiN coatings

Titanium nitride (TiN) coatings deposited by PVD and CVD have been increasingly used in industry for diverse applications. In this work, a plasma spray process of TiN deposition was investigated using a uniform design method. The experimental results of deposition efficiency, porosity, oxide content, microhardness and fracture toughness were regressed as the third order polynomial equations of the investigated process parameters. The relationships between the deposition efficiency, porosity, oxide content, microhardness and fracture toughness were examined in terms of coefficient of correlation. It was found that there were significant linear relationships between the deposition efficiency, oxide content, microhardness and fracture toughness. On the contrary, the linear relationships between them and the porosity were rather weak. Within the range of the uniform design of experiments, the deposition efficiency, microhardness and fracture toughness all increased, and the oxide content decreased while decreasing the argon flow rate and increasing the hydrogen flow rate. Using atomized liquid CO2 for cooling the substrate during plasma spraying, it is possible to further improve the quality of the TiN coating.