Effect of H₂ on Microstructure and Property of Nano-Titania Coatings

Nanostructured titania coatings were prepared by atmospheric plasma spraying using commercial nano-powder. The effects of plasma forming gas H2 on microstructure and anatase content of coatings were examined by X-ray diffraction and field emission scanning electron microscopy. Photocatalytic properties of coatings were evaluated through a photo degradation of methylene blue in water solution under ultraviolet illumination. The results obtained indicated that the TiO2 coating was a mixture of anatase and rutile. The anatase content of coatings increased with increase in the flow rate of plasma forming gas H2. The content of anatase was as high as 60% in the as-sprayed coatings under optimal spray parameters. The photocatalystic property was improved by the content of anatase in coatings. It was found that all fabricated TiO2 coatings exhibited photocatalytic activity for the methylene blue test regardless of spraying parameters.