Effect of Feedstock Powder Morphology on Cold-Sprayed Titanium Dioxide Coatings

The properties of cold-sprayed ceramic coatings depend not only on the process parameters but also on the feedstock powder characteristics. To clarify the effect of feedstock powder on cold spraying, two titanium oxide powders were used in this study: (1) nanopowder and (2) agglomerated powder prepared with nanoparticles and polyvinyl alcohol. The cross sections of the deposited coatings were observed by scanning electron microscopy (SEM). The results showed that the agglomerated powder with micrometer particles made of nano-sized particles passes successfully through the bow shock layer and reached the substrate, thus forming a coating. These particles are embedded into the substrate and form a strong interfacial coating/substrate bond. SEM images revealed that the metallic substrate undergoes plastic deformation, providing interlocking with the particles of the powder, and hence, reasonable bonding to the substrate.