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

nc-Ti C/a-C：H nanocomposite films were prepared by filtered cathodic arc technique. The influence of C_2H_2/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 Ti C crystallites are embedded in the amorphous matrix of a-C：H phase. C content in films increases with the flow ratio of C_2H_2/Ar, simultaneously, the crystallite size of TiC decreases. Contrary to the nc-Ti C/a-C：H films deposited by magnetron sputtering in which the sp3 C content increases with C_2H_2 flow rate, the increase of C_2H_2 flow rate leads to the increase of sp2 C content in films deposited by filtered cathodic arc technique. The nc-Ti C/a-C：H films deposited by cathodic arc technique have a pronounced hardness maximum of 30 GPa under the C_2H_2/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.