Study on chemical compatibility of TiO₂/(O'+β')-Sialon multi-phase ceramics

TiO₂/(O'+β')-Sialon, a new multi-phase ceramics, were successfully prepared on the basis of chemical-compatibility study on the system with home-made (O'+β')-Sialon powder and nano anatase powder as raw materials. Photocatalytic activity of TiO₂/(O'+β')-Sialon multiphase ceramics was investigated through its photocatalytic degradation to methylene blue (MB) solution. Thermodynamic calculation indicates that β'-Sialon and O'-Sialon react with TiO₂ at any temperatures and above 690 K in static status respectively. The experimental results show that in actual sintering conditions, both the two reactions took place above 1000°C, while the phase transformation from anatase to rutile occurred above 920°C. Metastable-state TiO₂/(O'+β')-Sialon composites with various phase composition of TiO₂ were obtained by sintering at various sintering rules not higher than 1000°C. TiO₂/(O'+β')-Sialon multiphase ceramics exhibit photocatalytic activity and the photocatalytic degradation rate of MB increases with the increase of TiO₂ content and decreases with the increase of sintering temperature and holding time. Relatively high photocatalytic activity was obtained for the materials sintered at 800°C and 900°C.