INFLUENCE OF BIAS VOLTAGE ON THE STRUCTURE AND MECHANICAL PROPERTIES OF Ti-Nb-C FILMS DEPOSITED BY DC DUAL MAGNETRON SPUTTERING

The films of the Ti-Nb-C system were deposited by direct current (DC) magnetron co-sputtering of composite Ti+Nb, and graphite targets onto Si substrates to which negative substrate bias in the range of -50 divided by-200 V was applied during film deposition. The microstructure, chemical bonds, and mechanical properties of films were comparatively investigated. The X-ray diffraction (XRD) analysis revealed that the peaks of the XRD spectra of the film obtained by co-spattering of the composite Ti+Nb and graphite targets are located in the intermediate region between the corresponding peaks of the Ti-C and Nb-C films. The X-ray photoelectron spectroscopy (XPS) showed that the Ti-C and Nb-C bonds prevail in the deposited Ti-Nb-C films. It was suggested that the Ti-Nb-C films are nanocomposite and consist of the crystallites of Ti1-xNbxCy solid solutions surrounded by amorphous carbon-based matrix. The Knoop hardness of the Ti-Nb-C film is highest (37.5 GPa) in the film deposited at -50 V substrate bias. The average friction coefficient determined before film delamination was the lowest (0.12) in that Ti-Nb-C film.