Influence of Cathodic Arc Current on ‎Structure, Mechanical and Tribological ‎Properties of TiC/a-C:H Nano-multilayer ‎Coatings

A cathodic arc ion plating system was used to produce TiC/a-C:H nano-multilayer coatings on silicon and cemented carbide substrates at cathodic arc currents in the range of 30-70 A. The microstructure, surface morphology and compositions of the TiC/a-C:H nano-multilayer coatings were analyzed by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The influence of the arc current on mechanical and tribological properties of the TiC/a-C:H nano-multilayer coatings was systemically investigated. The measurements show that the TiC/a-C:H multilayer coatings are composed of alternating layers of nanocrystalline TiC and amorphous hydrogenated carbon. The surface morphology of the TiC/a-C:H nano-multilayer coatings is controllable by the arc current. The ratio of Raman peak intensities ID/IG decreases and the full width at half maximum of G peaks (FWHMG) increases with the increasing of arc current. The content of hydrogen decreases from 26.5 at.% to 13.7 at.% while the content of TiC increases from 0.15at. % to 2.35 at.% as the arc current increases from 30 A to 70 A. The hardness of the TiC/a-C:H nano-multilayer coatings increases continuously up to 29.5 GPa at 70 A arc current. The average friction coefficients of the coatings keep at relatively lower values in the range of 0.1-0.2 as measured against Si3N4 balls. The results show significant influences of the cathodic arc current on the microstructure and properties of the TiC/a-C:H nano-multilayer coatings.