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 Ti(3)SiC(2) target onto Si(100) and high-speed steel substrates at 300 degrees C. The as-deposited films consisted of nanocrystalline (nc-) TiC(x) and amorphous (a-) SiC(x), as determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Annealing in vacuum up to 1450 degrees 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 TiC(x) 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 degrees 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. (c) 2006 Elsevier B.V. All rights reserved.