MECHANICAL CHARACTERISTICS AND STRUCTURE OF VACUUM ARC Ti-Cr-N COATINGS

The elemental composition, mechanical properties and structure of Ti-Cr-N coatings deposited in a wide range of nitrogen pressures from unfiltered and filtered vacuum arc plasma flows from Ti-Cr alloy cathodes containing 23 and 32 wt.% Cr have been investigated. It was found that for different deposition modes, the dependence of the Cr content in the coatings on the nitrogen pressure has a minimum near 1·10-3 Torr, which correlates with the maximum hardness Hμ. When plasma filtration or a cathode with a lower Cr content is used, the hardness maximum shifts to lower nitrogen pressures. The mechanisms that determine the elemental composition of the coatings are discussed. In the coatings deposited at a pressure of 9·10–4…5·10–3 Torr, the main phase is a nanocrystalline cubic solid solution of (Ti,Cr)N with a NaCl-type structure. Increasing the chromium content in the cathode contributes to the formation of an amorphous crystalline structure. Filtration effectively separates the droplet component from the plasma stream and produces coatings with reduced surface roughness. Nanostructured Ti-Cr-N coatings with high mechanical properties (Hμ ~ 35 GPa) containing ~ 20 wt.% Cr, which can be used to protect structural materials in power engineering and other nuclear industries.