The effect of post-treatments on the powder morphology of titanium dioxide (TiO2) powders synthesized for cold spray

In this study, a novel synthesis method of TiO2 powders that can be cold sprayed is presented. The synthesis technique is a simple hydrolysis method of titanyl sulfate (TiOSO4) in distilled water with a small addition of inorganic salt. At a relatively low hydrolysis temperature, pure anatase TiO2 can be obtained and post-synthesis treatments (annealing or hydrothermal treatment) do not alter this phase structure. The powder is agglomerated with fine nano primary particles, with different post-synthesis treatments leading to different TiO2 nanostructures. Annealing causes a significant growth of primary particles with the existence of internal pores within a particle. On the other hand, hydrothermal treatment produces a unique oriented agglomeration structure where the primary particles are agglomerated in one single crystal axes. It is believed that the synergistic effect of inorganic ion adsorption and post-treatments results in the observed nanostructures. After cold spraying, it is revealed that these TiO2 powders could be deposited via supersonic solid phase deposition (cold spray).