Abstract
Functional titanium dioxide coatings have a high potential for photocatalytic applications. However, the high process temperatures of conventional thermal spray methods lead to undesirable phase transformations. Cold gas spraying seems to be beneficial, since for ceramic coatings no phase transformations have been observed so far. In this study, bonding of cold-sprayed ceramic particles on metal substrates is elucidated by investigating single impacts obtained from wipe tests. Different feedstock powders were used, consisting of agglomerated titanium dioxide nanoparticles. The single particle impacts were investigated by scanning electron microscopy and confocal microscopy. The results demonstrate that bonding of particles is influenced by the substrate material, substrate temperature, powder properties and spray conditions. In addition, powder characteristics seem to be of particular importance. The results allow for conclusions regarding favorable conditions for cold spraying of ceramics.
