Abstract
In the present study, TiO2 and TiO2-Al composite coatings were prepared by HVOF spraying using reconstituted nanosized feedstock powders prepared via the spray drying technique. In the flame, the powders were injected by two methods: internal injection i.e. as in conventional HVOF process and external injection i.e. outside the torch nozzle. The microstructure of the coatings was characterized by scanning electron microscopy and X-ray diffraction. It was found that the amount of anatase in the coatings depends on the nature of the powder and also on the type of the injection method. The coatings were tested for their photocatalytic properties regarding the conversion rate of nitrogen oxides. Coatings elaborated by external injection presented a better photocatalytic activity than those obtained by the conventional HVOF process.
