Tribological and Corrosion Characteristics of Ti6Al4V Coatings Cold Sprayed with Nitrogen and Helium Propellant Gases

Abstract

The tribological and corrosion characteristics of Ti6Al4V coatings on Ti6Al4V substrates with nitrogen (N2) and helium (He) propellant gases cold sprayed via a high pressure cold spray process were investigated because different masses of the N2 and He working gases could affect the velocities of Ti6Al4V particles during the cold spraying and consequently the properties of the coatings. The more uniform and denser structure of the Ti6Al4V coatings with a lower porosity level was achieved with He working gas. As a result, the Ti6Al4V coatings deposited with the He working gas had a higher hardness than those deposited with the N2 working gas. The tribological results showed that the use of He gas during the cold spraying produced the more wear resistant Ti6Al4V coatings associated with their higher hardness. The denser Ti6Al4V coatings deposited with the He gas had a lower anodic current density in a NaCl solution than those deposited with the N2 working gas. It is clear that the wear and corrosion resistances of the Ti6Al4V coatings were significantly influenced by the propellant gases during the cold spray deposition.