Study on chemical compatibility of TiO_2/(O′+β′)-Sialon multi-phase ceramics

TiO_2/(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 TiO_2/(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 TiO_2 at any temperatures and above 690K in static status,respectively.The experiment results show that in actual sintering conditions,both the two reactions took place above 1000℃,while the phase transformation from anatase to rutile occurred above 920℃.Metastable-state TiO_2/(O′+β′)-Sialon composites with various phase composition of TiO_2 were obtained by sintering at various sintering rules not higher than 1000℃.TiO_2/(O′+β′)-Sialon multiphase ceramics exhibit photocatalytic activity and the photocatalytic degradation rate of MB increases with the increase of TiO_2 content and decreases with the increase of sintering temperature and holding time.Relatively high photocatalytic activity was obtained for the materials sintered at 800 and 900℃.