Phase Formation during Deposition of TiO2 Coatings through High Velocity Oxy-Fuel Spraying

• Published in: MATERIALS TRANSACTIONS Vol. 47; no. 7; pp. 1690 - 1696
• Main Authors: Li, Chang-Jiu, Yang, Guan-Jun, Wang, Yu-Yue, Li, Cheng-Xin, Ye, Fu-Xing, Ohmori, Akira
• Format: Journal Article
• Language: English
• Published: Sendai The Japan Institute of Metals and Materials 2006; Japan Science and Technology Agency
• Subjects: Anatase; Catalytic activity; Coatings; crystalline; Fuels; Gas flow; high velocity oxy-fuel; High velocity oxyfuel spraying; phase formation; Photocatalysis; Powder spraying; Rapid solidification; Raw materials; Rutile; Titanium dioxide; titanium oxide
• ISSN: 1345-9678; 1347-5320
• DOI: 10.2320/matertrans.47.1690

The crystalline structure of TiO2 coating is of significant importance for controlling its property and performance, such as photocatalytic activity. The aim of this study is to examine the phase formation mechanisms during high velocity oxy-fuel (HVOF) spraying of TiO2 coating. TiO2 coatings were deposited under different spray conditions using both anatase powder and rutile powder as feedstocks. The results showed that the anatase content in the coatings was increased with the increase of fuel gas flow when using the rutile powder as feedstock. A TiO2 coating of anatase content up to 35% can be obtained by well-melted particles. The high content of anatase phase possibly resulted from rapid solidification and cooling process of the particles. The anatase content in the TiO2 coating deposited with an anatase powder in partially melted state reached 55–65%. The coating deposited by well-melted anatase powder contained the same anatase content as that by rutile powder. A model was proposed to explain the phase formation within the coatings deposited through HVOF spraying.