Effects of Gas Temperature, Gas Pressure, and Particle Characteristics On Cold Sprayed Pure Titanium Coatings
W. Wong, A. Rezaeian, S. Yue, McGill University, Montreal, QC, Canada; E. Irissou, J. G. Legoux, Industrial Materials Institute / -National Research Council Canada, Boucherville, QC, Canada
Cold spraying titanium powder is challenging. Contrary to other pure metals such as copper, nickel, and aluminum, titanium coatings are found to be porous even with very high particle velocity obtained by using helium as propelling gas.
In this work, the influence of four parameters on the deposition efficiency, microstructural features, and mechanical properties are systematically investigated in order to optimize cold spray titanium coatings. (1) The influence of particle temperature is studied by comparing the results obtained from two spray guns, namely CGT (Cold Gas Technology-GmbH) Kinetiks 3000 and Kinetiks 4000. (2) The isolated effect of powder sizes is studied using a powder classifier. (3) The effect of oxygen content in the starting powder is investigated by performing a controlled oxidation of the powder. (4) The effect of gun traverse speed is investigated.
For all conditions, the surface temperature is monitored using high speed infrared imaging and the particle velocity is measured using optical diagnostics.
Summary: In a previous investigation, it has been found that large pores were formed in cold sprayed titanium coating where nitrogen was used as accelerating gas and that the resulting coating was not as dense as the one found for pure nickel coating. This research aims to further optimize cold spray parameters for titanium powder in order to meet requirements for coating build-up applications.
This work reports on the coating properties of pure Ti on mild steel substrate. The deposition characteristics were studied by examination of microstructure evolution of the coatings. Samples were sprayed using CGT Kinetiks 4000 system (Cold Gas Technology-GmbH) with two gun temperatures of 500 and 800 °C and gun pressures of 30 and 40 bars using nitrogen as propelling gas. The effect of two powder sizes (fine and coarse), as well as three oxygen levels on the final coating properties were investigated in terms of deposition efficiency, porosity, and mechanical properties. Different gun traverse speeds were also studied in order to evaluate their effect on substrate temperature and in order to facilitate the optimization of the coating. In addition, the effect of substrate hardness as well as material on the coating process was investigated.
