Influence of helium and nitrogen gases on the properties of cold gas dynamic sprayed pure titanium coatings

This study investigated the effect of the type of gas used, nitrogen and helium, during cold spraying of titanium coatings. In all conditions, the propelling gases\u2019 temperature and pressure were attuned to attain three similar particle velocities for each gas. Coatings were characterized by SEM and XPS. Deposition efficiency, coating microhardness, and porosity were evaluated for all conditions. Results show that for the same particle impact velocity, the deposition efficiency and coating density were mostly the function of the surface temperature, which in turn was influenced by spray parameters. It is shown that loosely-bonded particles at the surface can be detached by the passage of high pressure supersonic gas stream. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimized spray parameters with He and the corresponding average particle velocity was measured at 1173 m/s.Peer reviewed: YesNRC publication: Ye