Nanostructure, mechanical and tribological properties of reactive magnetron sputtered TiCx coatings

This study describes the correlation between microstructure, mechanical and tribological Properties or TiCx, coatings (with x being in the range of 0-1.4). deposited by reactive magnetron sputtering from a Ti target in Ar/C2H2 mixtures at similar to 200 degrees C. The mechanical and tribological properties were found to strongly depend on the chemical composition and the microstructure present. Very dense structures and high hardness, combined with low wear rates and friction coefficients, were observed for coatings with chemical composition close to TiC. X-ray diffraction and X-ray photoelectron spectroscopy analysis. used to evaluate coating microstructure, composition and relative phase fraction, showed that low carbons contents in the coatings lead to sub-stoichiometric nanocrystalline TiC, coatings being deposited, whilst higher carbon contents gave rise to dual phase nanocomposite coatings consisting of stoichiometric TiC nanocrystallites and free amorphous Carbon. Optimum performance was observed for nanocomposite TiC1,1 coatings, comprised of nanocrystalline nc-TiC (with ail average grain size of similar to 15 nm) Separated by 2-3 monolayers of an amorphous a-DLC matrix phase. (C) 2008 Elsevier B.V. All rights reserved.