Tribological and mechanical behaviors of TiN/CNx multilayer films deposited by magnetron sputtering

TiN/CNx multilayer films with bilayer periods of 4.5–40.3 nm were deposited by direct-current magnetron sputtering. Layer morphology and structure of the multilayered films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The TiN/CNx multilayers exhibited coherent epitaxial growth due to the mutual growth-promoting effect at small bilayer period and some crystalline regions going through the interface of TiN/CNx. Nanoindentation tests showed that the hardness of the multilayers varied from 12.5 to 31 GPa, with the highest hardness being obtained with a bilayer period of 4.5 nm. The tribological properties of the films were investigated using a ball-on-disk tribometer in humid air, and the TiN/CNx multilayer with a bilayer period of 4.5 nm also exhibited the lowest friction coefficient and the highest wear resistance.