Electrodeposition, microstructure and tribological performance of Ni/(N) incorporated diamond-like carbon films

Abstract

Modified diamond-like carbon (DLC) films doped with nickel and nitrogen and coated with nickel interlayer were synthesized by a combined method of pulsed and direct-current electrodeposition. The growth mechanisms of the co-doped film and the influences of different nitrogen concentrations on the microstructure and friction performance of the films were explored. The results illustrated that the smallest grain size and the densest binding of the film were achieved when the carbamide concentration was 0.12 g/L. Raman and XPS analysis revealed that the appropriate addition of nitrogen is conducive to the generation of sp3-C. Meanwhile, most of the nickel exists in the amorphous carbon matrix as crystalline clusters, while the nitrogen is preferentially bonded with the carbon matrix at the cluster interface in the form of low-energy double bonds. Furthermore, Ni/ (0.12 g/L) N-DLC films demonstrated the maximum microhardness (461.50 HV) and excellent wear resistance, which benefits from the compact structure, high sp3-C content and formation of the proper amount of CN groups.