Effects of working gas on wear and corrosion resistances of cold sprayed Ti-6Al-4V coatings

In this study, the wear and corrosion resistances of cold sprayed Ti-6Al-4V (Ti64) coatings on commercial Ti64 substrates using nitrogen (N2) and helium (He) working gases were systematically investigated. The denser microstructure of the Ti64 coating with a lower porosity level was achieved with He working gas. Therefore, the Ti64 coating deposited with He working gas had the higher hardness than the one deposited with N2 working gas. The Ti64 coating deposited with He working gas had higher adhesion strength than the one deposited with N2 working gas. The tribological results showed that the use of He working gas during the cold spraying gave rise to the higher abrasive wear resistance of the Ti64 coating via its higher hardness. In addition, the Ti64 coating deposited with He working gas did not show any fatigue micro-cracks on its wear track during the prolonged sliding probably due to the relatively strong bonding between sprayed Ti64 particles. It was found that the Ti64 coating deposited with He working gas had lower anodic dissolution in 0.6 M NaCl solution compared to the one deposited with N2 working gas as a result of its lower porosity level.