Synthesis and mechanical properties of Ti–Si–C films by a plasma-enhanced chemical vapor deposition

Ti–Si–C films were synthesized on WC–Co substrate by a plasma-enhanced chemical vapor deposition (PECVD) technique using a gaseous mixture of TiCl4, SiH4, CH4, Ar, and H2. Effects of process parameters, such as deposition temperature and gas ratio, Mx= [SiH4/(SiH4+TiCl4)], on the microstructure and mechanical properties were systematically investigated in this work. From instrumental analyses of HRTEM, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), it was concluded that the Ti–Si–C film was a fine composite of TiC crystallites with amorphous SiC phase. The Si addition caused a microstructural modification of the TiC film to the fine composite with TiC crystal size refinement by interpenetration of amorphous SiC phase among TiC crystallites. The microhardness of the Ti–Si–C film increased from ∼22 GPa of TiC to ∼33 GPa at Si content of 5.2 at.%. In addition, the average friction coefficient against steel decreased from 0.4 of TiC film to 0.28 of Ti–Si–C film containing 5.2 at.% Si. The microhardness value of Ti–Si–C film was largely dependent on the deposition temperature.