Annealing studies of nanocomposite Ti–Si–C thin films with respect to phase stability and tribological performance

Nanocomposite Ti–Si–C thin films were deposited by dc magnetron sputtering from a Ti3SiC2 target onto Si(1 0 0) and high-speed steel substrates at 300 °C. The as-deposited films consisted of nanocrystalline (nc-) TiCx and amorphous (a-) SiCx, as determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Annealing in vacuum up to 1450 °C resulted in improved crystallinity and a decreased volume fraction of the amorphous phase. Additionally, differential scanning calorimetry (DSC) was used to monitor heat flows connected to the respective reactions in the material, where a broad exothermic peak attributed to grain growth of crystalline TiCx appeared, while an exothermic reaction related to the formation of Ti3SiC2 was not detected. Tribological testing in a ball-on-disk setup was conducted at room temperature, 500 and 700 °C against an alumina counterpart. The room temperature measurement resulted in a coefficient of friction value of 0.8; at elevated temperatures the coefficient of friction decreased to 0.4.