Phase Formation of Nano-TiO{sub}2 Particles during Flame Spraying with Liquid Feedstock

摘要

The nanostructured TiO{sub}2 photocatalytic coatings were synthesized through flame spraying with liquid feedstock under different conditions. The nanostructured TiO{sub}2 deposit of substantial anatase phase was annealed at different temperatures. X-ray diffraction analysis showed that significant transformation from anatase to rutile occurred at a temperature above 600℃. However, thermal analysis suggested that the phase transformation from anatase to rutile started at a temperature from 400 to 500℃. It was found that the grain size of rutile phase was larger than that of anatase. The deposits annealed at temperatures lower than 450℃ were photocatalytically active. However, the deposit annealed at 500℃, which contained 95% anatase crystalline, became photocatalytically inactive. Based on the experimental findings, a model is proposed to explain the phase transformation of the nano-TiO{sub}2 particles and the phase formation in flame-spraying of nanostructured TiO{sub}2 deposit with liquid feedstock.