Improved structural, mechanical, corrosion and tribocorrosion properties of Ti45Nb alloys by TiN, TiAlN monolayers, and TiAlN/TiN multilayer ceramic films

Abstract

In this study, TiN, TiAlN monolayers, and TiAlN/TiN multilayer ceramic films on the surface of Ti45Nb substrates were formed via the cathodic arc physical vapour deposition process. The samples were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy, nano-indentation testing and surface tension testing. The corrosion performance of the samples was evaluated via potentiodynamic polarization and electrochemical impedance spectroscopy measurements and their tribocorrosion behaviour was evaluated by a ball on flat reciprocating tribotester in which the tribological contact was immersed in the electrolyte. The obtained structural and mechanical results indicated that multilayer films have finer grain sizes, and more stable and harder film structures compared with the monolayer coatings. Moreover, the surfaces of the samples exhibited different wetting characteristics. While uncoated and single layer (TiN, TiAlN) coatings showed hydrophilic behaviour, the multilayer coating exhibited hydrophobic behaviour. During the corrosion and tribocorrosion tests, all of the coatings showed a protective feature due to the ceramic structure of the coatings against corrosion and tribocorrosion. Among all of the ceramic coatings, the best results were obtained for the multilayer film.