Effect of Si addition on the microstructure, mechanical properties and tribological properties of Zr–Si–N nanocomposite coatings deposited by a hybrid coating system

Zr–Si–N coatings with various Si contents were synthesized by a hybrid coating system combining arc ion plating and d.c. magnetron sputtering techniques. The influence of the Si content on the microstructure, mechanical properties and tribological properties of the Zr–Si–N coatings was investigated. The results showed that as the Si content increased from 0 to 5.8 at.%, the coatings transformed from a columnar ZrN to nanocomposite structure with a nano-sized ZrN crystallites embedded in amorphous Si3N4 matrix and further increases of Si content lead to amorphous-like coatings. The maximum hardness (H) of 33 GPa, Youngʹs modulus (E) of 265 GPa, and H/E⁎ value of 0.12 were obtained at Si content of 5.8 at.% in the Zr–Si–N coatings, respectively. The coating with the lowest friction coefficient and the best wear resistance was also obtained at Si content of 5.8 at.%, which was mainly contributed to high value of H/E⁎ and formation of SiO2 or Si(OH)4 self-lubricating layer due to the interface tribo-chemical reaction.