Cold Spraying of TiO2 Photocatalyst Coating With Nitrogen Process Gas

Titanium dioxide (TiO2) is a promising material for photocatalyst coatings. However, it is difficult to fabricate a TiO2 coating with anatase phase by conventional thermal spray processes due to a thermal transformation to rutile phase. In this paper, anatase TiO2 coatings were fabricated by the cold spray process. To understand the influence of process gas conditions on the fabrication of the coatings, the gas nature (helium or nitrogen) and the gas temperature are investigated. It was possible to fabricate TiO2 coatings with an anatase phase in all spraying conditions. The process gas used is not an important factor to fabricate TiO2 coatings. The thickness of the coatings increased with the process gas temperature increasing. It indicates that the deposition efficiency of the sprayed particles can be enhanced by controlling the spray conditions. The photocatalytic activity of the coatings is similar or better than the feedstock powder due to the formation of a large reaction area. Concludingly, cold spraying is an ideal process for the fabrication of a TiO2 photocatalyst coating.