Effect of pulsed substrate bias on the structure and properties of nitride coatings deposited by filtered cathodic arc plasma

The results of studies of nitride coatings deposited using a cathodic vacuum arc plasma source with a rectilinear type filter are presented. The effect of parameters of high voltage substrate bias pulses on the deposition rate, composition, structure and mechanical properties of coatings based on TiN and CrN, including multi-component ones with the additions of Al, Si, Zr, Y, Re, Nb, Hf, was analyzed. With different regimes of bias potential the formation of coatings with a nanocrystalline cubic structure (of the NaCl type) and close to stoichiometric nitrogen content and high hardness of 25…36 GPa is ensured. It was found that changing the amplitude, duration and frequency of pulses allows to effectively controlling the morphology, size of crystallites, texture and stress level in coatings, which effects their mechanical properties. The use of a pulse bias potential with an amplitude of 1…2 kV, a frequency of 10…20 kHz and duty cycle of 10…15% makes it possible to form a homogeneous dense nanostructure with a [110] or [100] texture, an optimal stress level 4…5 GPa and a smooth surface in coatings of different compositions. It is shown that such a structure provides improved resistance of coatings to various types of wear. Unequivocal correlations were not found between the hardness of the coatings, the modulus of elasticity and their wear. (author)