Nanostructured surfaces

Influence of the nitrogen pressure on the structure and mechanical properties of vacuum arc VNx coatings
Kuprin A.S.1, Kolodiy I.V.1, Ovcharenko V.D.1, Belous V.A.1, Bortnitskaya M.A.1, Gilewicz A.2, Warcholinski B.2
1 National Science Center “Kharkov Institute of Physics and Technology”, 1 Akademichna st., 61108, Kharkov, Ukraine. 
E-mail: kuprin@kipt.kharkov.ua
2 Koszalin University of Technology, Faculty of Technology and Education, Koszalin, Poland.

Due to the good thermal, catalytic properties and tribological features, a low wear rate and friction coefficient, the vanadium nitride thin coatings can be widely applied [1, 2]. The evolution of phase composition from metallic vanadium through intermediate phases up to δ-VN phase supersaturated with nitrogen were investigated in thin films deposited by reactive, pulsed magnetron sputtering from vanadium target [3]. Vacuum arc evaporation method allows to obtain the nitride coatings characterized by high adhesion, density and quality, but influence of nitrogen pressure on structure and properties of V-N system were not studied yet.
The VNx coatings were deposited using unfiltered vacuum arc plasma method in a “Bulat” system equipped with a V (99.9 %) cathode. A deposition process was performed at substrate bias voltage of -100 V, arc current of 80 A and nitrogen pressure ranged from 0.001 to 3.0 Pa. 
The deposition rate, surface morphology, microstructure and chemical composition of VNx coatings were investigated using scanning electron microscopy, x-ray diffraction analysis and energy dispersive x-ray spectroscopy. The mechanical properties of coatings were characterized using nanoindentation.

1.	Hajihoseini H., Kateb M., Ingvarsson S., Gudmundsson. J.T. Effect of substrate bias on properties of HiPIMS deposited vanadium nitride films // Thin Solid Films.-2018.-663.-P. 126-130.
2.	Franz R., Mitterer C. Vanadium containing self-adaptive low-friction hard coatings for high-temperature applications: A review // Surf. and Coat. Technol.-2013.-228, -P. 1-13.
3.	Suszko T., Gulbinski W., Urbanowicz A., Gulbinski W. Preferentially oriented vanadium nitride films deposited by magnetron sputtering // Materials Letters.-2011.-65, N 3.-P. 2146-2148.