Microstructure and mechanical properties of hard Ti–Si–C–N films deposited by dc magnetron sputtering of multicomponent Ti/C/Si target

Quaternary Ti–Si–C–N films with different silicon contents were deposited on Si (100) substrates by dc magnetron sputtering of multicomponent Ti/C/Si target in an Ar/N2 gas mixture. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation, and scratch tests have been employed to characterize the films. The films were found to have a nanocomposite structure composed of nanocrystallites solely or of those surrounded by mixed amorphous phase, namely: nc-Ti/nc-TiNx/nc-Ti(C,N), nc-Ti(C,N)/a-TiSi/a-SiNx/a-C/ a-CN, or nc-Ti(C,N)/nc-TiSi2/a-SiNx/a-C/a-CN depending on the silicon content in the film. The nanohardness and elastic modulus of films first increased with adding silicon and reached their maximum values at 3.4 at.% Si, and then decreased. The highest nanoindentation hardness was 29 GPa which is higher than that of pure TiN coatings. The friction coefficient of Ti–Si–C–N films generally decreased with adding silicon, and with 3.4 at.% Si exhibited the lowest value.

Research highlights
► Approach for deposition hard Ti-Si-C-N films by dc magnetron sputtering of single target composed of Ti, Si, C elements.
► Control of the content of elements in film through variation of amount of them in target.
► The microstructure evolution of Ti-Si-C-N films is studied depending on silicon content in film.