THE DEVELOPMENT OF NANO-PHOTOCATALYTIC TiO_2 COATINGS BY THERMAL SPRAYING

摘要

TiO_2 coatings were prepared by High Velocity Oxy-Fuel (HVOF) spraying using agglomerated nano-TiO_2 powders (200nm, 30nm and 7nm). The effects of spraying conditions on anatase phase ratio have been investigated. Although the anatase phase ratio drastically decreased with increasing fuel gas pressure in the case of 7nm-powders, while 200nm and 30nm powders provided higher anatase ratio. Especially, 30nm was optimum size and therefore, the anatase ratio more than 70% could be achieved These coatings showed photo-catalytic degradation of CH_3CHO gas. The sprayed TiO_2 coating using 30nm-agglomerated powder showed higher degradation rate because of higher anatase ratio.