Structural and mechanical properties of TaN/a-CNx multilayer films

TaN/a-CNx multilayer films with modulation periods of 8.5–12 nm are deposited on Si wafers and titanium alloy substrate using direct current magnetron sputtering. The morphology and structure of the films are characterized by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Mechanical and tribological properties are tested by nanoindention and ball-on-disk tribometer. Columnar structure exists in single TaN film and TaN/a-CNx multilayer with 0.5 nm-CNx, while the columnar crystalline can be better interrupted by thicker a-CNx layers. The hardness of all the TaN/a-CNx multilayers is higher than that of the single TaN film. The maximum hardness of 31.0 GPa and the friction coefficient of 0.12 are obtained in the multilayer film with 2 nm-CNx. According to our research, the thickness of a-CNx in multilayer is best to distribute within 1–2 nm. The wear rates under 5 N are in the order of 10− 15 m3 m− 1 N− 1 for the multilayer films and increased by 1 order of magnitude 10− 14 for the TaN film (1.6 × 10− 14 m3 m− 1 N− 1).