Abstract
In the present research, NOx elimination coating photocatalyst was tried to be made by a few kinds of thermal spray processes, and the possibility for the fabrication of coating photocatalyst by thermal spray process was fundamentally investigated. NOx elimination characteristic of the fabricated coatings was evaluated in the simulative polluted environment, and the relationship between the fraction of anatase phase in the coating, the coating thickness and the NOx elimination characteristic of the coating was evaluated.
It was possible to leave the anatase phase in the coatings by both gas flame spraying and atomospheric plasma spraying. The fraction of anatase phase, however, was quite limited by these methods. Fairly high fraction of the anatase phase could be left in the coating by using HVOF spraying method. At this moment, HVOF spraying seems to be the best process. The photocatalitic NOx elimination property was recognized in the coatings fabricated by the thermal spraying. The NOx elimination ratio of the sprayed coating reached to the maximum just after the irradiation of the ultraviolet rays and subsequently decreased, just similar to the tendency of the original powder. An effective reaction layer of the coating photocatalyst was observed near the coating surface region, and the thickness of the layer was approximately 25μm in the coating obtained by HVOF spraying.
