Comparison of the Photocatalytic Behavior of TiO₂ Coatings Elaborated by Different Thermal Spraying Processes

In this paper a comparative study on the microstructure and photocatalytic performances of titanium dioxide coatings elaborated by various thermal spraying methods (plasma spraying in atmospheric conditions, suspension plasma spraying and high-velocity oxy-fuel spraying) was proposed. Agglomerated spray-dried anatase TiO₂ powder was used as feedstock material for spraying. Morphology and microstructural characteristics of the coatings were mainly studied by scanning electron microscopy and X-ray diffraction. The photocatalytic behavior of the TiO₂-based surfaces was evaluated from the conversion rate of gaseous nitrogen oxides (NOx). It was found that the crystalline structure strongly depended on the technique of thermal spraying deposition. Moreover, a high amount of anatase was suitable for the photocatalytic degradation of the pollutants. Suspension plasma spraying permitted to retain the original anatase phase and to obtain very reactive TiO₂ surfaces for the nitrogen oxides removal.