The Research Of Self-cleaning Glasses With TiO₂ Thin Film

Self-cleaning glass has very broad applying market,in our country the research and development of it is very important.The present industrialization production has some disadvantages such as complicated technology and too much consume of energy. The light-induced hydrophilicity self-cleaning glass could be improved by using the dopants.In the experiments of this paper,slide glass plates were used as substrates.The TiO₂ thin film, TiO₂/SiO₂ double layers film, TiO₂-Al₂O₃ compound film and TiO₂-WO₃ compound film were prepareed by traditional sol-gel soak-lift way.The results of experiments showed that TiO₂/SiO₂ double layers film and TiO₂ thin film doped with Al₂O₃ and WO₃ both could improve the hydrophilicity of TiO₂ films . The TiO₂-WO₃ compound film had the best hydrophilicity,compared with the pure TiO₂ film self-cleaning glass.In the experiment,the concertration of TiO₂ sol is 0.5 mol/L, the device for film preparation was designed by ourselves, thickness of TiO₂ thin film we got was about 40nm. The contact angle of the TiO₂ film surface fell to 15° through 1.2h and kept 10° at last.A layer of SiO₂ thin film was coated on the silde glass plate before coating TiO₂ film for preventing sodium ions in the glass to diffuse in the TiO₂ film to effect the hydrophilicity. To the TiO₂ film,the surface of TiO₂/SiO₂ double layers film was rougher, and there was microholes structure.Therefore,the hydrophilicity of film was improved, the contact angle of film surface could fall to 12° in 5 min and keep 8° at last.In this paper, we studied the difference of hydrophilicity and photocatalytic activity of TiO₂/SiO₂ double layers film which was baked in different temperatures, and found that the film baked in 600°C for 1h had the better hydrophilicity and photocatalytic activity.For improving the light-induced hydrophilicity, Al₂O₃ was doped in the TiO₂ film,because Al₂O₃ has good effect of controlling phase transformation of TiO₂ and preventing the growing of TiO₂ crystal particle.The results showed that the saturated contact angle of TiO₂ film surfaces fell down greatly.Furthermore,the more doping Al₂O₃,the less the contact angle,but the falling speed of contact angle was slower.For controlling the directional movement of electrons and holes and prolonging the life-span of the surface holes, WO₃ was doped in TiO₂ film.The results of experiment showed that the film made by this way had more hydrophilicity and more photocatalytic activity.Another important phenomenon was that the absorb edge of UV moved towards the visible light by doping WO₃.The research of WO₃-TiO₂ compound film is an important new point of this paper.In this paper,the use properties of self coating glasses were investigated and the microstructure and crystal composition of TiO₂ film were analysed by AFM and XRD.