Structure and mechanical properties of nc-TiC/a-C:H nanocomposite films deposited by filtered cathodic arc technique

Abstract

nc-TiC/a-C:H nanocomposite films were prepared by filtered cathodic arc technique. The influence of C2H2/Ar flow ratio on the composition, structure, and mechanical properties of films was investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nanoindentation, and ball-on-disc tribometry. The films show a nanocomposite structure in which TiC crystallites are embedded in the amorphous matrix of a-C:H phase. C content in films increases with the flow ratio of C2H2/Ar, simultaneously, the crystallite size of TiC decreases. Contrary to the nc-TiC/a-C:H films deposited by magnetron sputtering in which the sp3 C content increases with C2H2 flow rate, the increase of C2H2 flow rate leads to the increase of sp2 C content in films deposited by filtered cathodic arc technique. The nc-TiC/a-C:H films deposited by cathodic arc technique have a pronounced hardness maximum of 30 GPa under the C2H2/Ar flow ratio of 12. Tribological performance of films is controlled by the sp2 content in films. Higher sp2 content promotes the formation of graphite-like transfer layer during sliding, and results in lower wear rate and friction coefficient.