Study Of The Structures And Properties Of TiO₂ Solar-controlling And Self-cleaning Coated Glass Prepared By APCVD Method

With the aggravation of energy crisis and environmental issue, architectural energy-saving has drawn people’s attentions. The research of coated glass is one of the most important parts of architectural energy-saving technology. Especially, solar-controlling and self-cleaning coated glass has become the focus of architectural energy-saving materials. TiO2 is the first choice of the solar-controlling and self-cleaning thin film materials, due to its chemical stability, nontoxic, cheap, high refractive index, high catalytic activity and super hydrophilic property. In this paper, we review the applications of TiO2 in solar-controlling and self-cleaning. We design the coating reactor jet by ourselves. We prepare a serious of TiO2 solar-controlling and self-cleaning coated glass. We study the microstructure and properties of TiO2 we prepared. Considering the industrial sample, we propose several methods to improve the solar-controlling and self-cleaning properties. The contents and results are as follow.(1) We have successfully designed an APCVD coating reactor which is of enhanced convective heat transfer. In the premise of assuring the homogeneity of the film coated gas and the stability of laminar conditions, we enhanced convective heat transfer to preheat the precursor gas. Consequently, we can broaden the temperature limits and increasing the film deposition rate.(2)We prepared several samples in different deposition temperature, jet moving speed and the distance between jet and substrate.TiO2 film is composed of pure anatase. The reaction activation energy of TiO2 is 36.55kJ/mol. With the increasing of deposition temperature, the film deposition rate is 33.7nm/s. With the jet moving speed accelerating, the thickness of the film decreasing. When the distance between jet and substrate is far to 9mm, the film becomes uniformity. The best sample is 600℃、 0.1mm/s、9mm, which is of 80% visible transmittance. After 2 hours ultraviolet radiation, it shows outstanding super hydrophilic and can degrade 50% RhB. We have prepared a serious of 200nm anatase Nb:TiO2 film with 20at%Nb. Compared with pure TiO2 film, the Nb:TiO2 film has lower near-infrared transmittance, about 60%, which enhanced the effect of solar-controlling. Also after 1 hour ultraviolet radiation, it is of super hydrophilic which is better than pure TiO2 film.(3) The online TiO2 solar-controlling and self-cleaning coated glass in product line has been investigated. The film is deposited at 17nm/s which is about 40nm and composed of grain less than 10 nm. The film is of bad crystallinity and low density. It is of bad hydrophilic property which shows hydrophilic property after 4 hours ultraviolet radiation. Also it doesn’t show obvious photocatalytic activity property.(4) According to our results, when we coat film on the float glass production line, if we want to optimize the crystallinity, solar-controlling and self-cleaning properties of TiO2 films, we can optimize film coating reactor thermal efficiency, increase deposition temperature, slow down the reactor moving, keep a appropriate distance between reactor and glass belt.