Nanostructured surfaces

Effect of substrate bias on structure and mechanical properties of vacuum arc deposited NbN coatings
Klimenko I.O.1, Tolmachova G.N.1, Kolodiy I.V.1, Vasilenko R.L.1, Reva S.G.1, Belous V.A.1, Kuprin A.S.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: ilyaklimenko91@gmail.com
2 Koszalin University of Technology, Faculty of Technology and Education, Koszalin, Poland..

Among hard protective coatings based on transition metal nitrides deposited by PVD techniques, niobium nitride (NbN) is a very attractive material because of its good thermal expansion similar to that of widely used tool steels, high melting point, high electrical conductivity and superior chemical inertness [1]. The properties of the vacuum arc coatings strongly depend on the technological parameters of deposition, such as reactive gas pressure, deposition temperature or substrate bias voltage. The investigations of the effect of bias voltage on the microstructure and mechanical and tribological properties (adhesion, friction coefficient, wear) of NbN thin films are very limited [2]. 
The aim of these investigations is to assess the difference in structural and mechanical properties of NbN coatings deposited using vacuum arc evaporation with negative substrate bias voltage ranging from -50 to -300 V.
The deposition rate, surface morphology, microstructure, chemical composition and mechanical properties of NbN coatings were investigated using scanning electron microscopy, X-ray diffraction analysis, energy dispersive x-ray spectroscopy and nanoindentation. 

1.	J. Ding, T. Zhang, H. Mei, J.M. Yun, S.H. Jeong, Q. Wang, K.H. Kim. Effects of Negative Bias Voltage and Ratio of Nitrogen and Argon on the Structure and Properties of NbN Coatings Deposited by HiPIMS Deposition System // Coatings 2018, 8, 10; doi:10.3390/coatings8010010.
2.	N. Cansever. Properties of niobium nitride coatings deposited by cathodic arc physical vapor deposition // Thin Solid Films 515 (2007) p. 3670–3674.