Study On Synthesis And Properties Of Silica Aercgel Film And Composite Coated Glass With Energy Saving Function

With building energy cost taking up a large part of the total energy lost, designation of energy saving building has become more and more important. On the basis of researching papers in the field of energy saving glass, this paper proposes the idea of applying silica aerogel film, which is a kind of material with high porosity, low density and low thermal conductivity, in the architecture energy saving coated glass as thermal insulating layer. Besides, in order to reduce energy lost, this paper also proposes to combine low-e film, silica aerogel film and solar control film to obtain a composite coating on glass.In the synthesis of silica aerogel film, sol-gel method and ambient pressure drying method were adopted, and MTMS was chosen as alkyl-functional precursor. The effect of different synthesis parameters on the morphology, porosity and optical performance of silica film was investigated. The result indicated that the porosity increased with the increase of solvent amount and heat treating temperature; film cracking was reduced when increasing the solvent amount and decreasing the concentration of NH4OH, and glycerol was proved to be effective in reducing the cracking; with the heat treating temperature increasing, the thickness decreased and film transmittance increased. The thickness of the silica aerogel film sample prepared under the optimized condition was710nm, the transmittance was about85%, and the thermal conductivity of the coated glass decreased from1.332W/mK to1.302W/mK.In the3-layer composite coating system, the low-E function was provided by the SnO2:F (FTO) glass, SiO2aerogel film was coated on the FTO glass to decrease the thermal conductivity from3.615W/m to3.368W/mK. TiO2film was deposited on the top using CVD method. The effect of deposition temperature and the inflow ratio of TiCl4:N2on the structure and optical performance of the composite coating was studied. The result showed that anatase phase TiO2was obtained at deposition temperature from500to600℃. The visible and near-infrared reflectance increased with the increase of the anatase TiO2amount. When the deposition temperature is550℃and inflow ratio of TiCl4:N2is0.2:0.8, TiO2particles are uniform and compact, ideal composite coating with certain reflectance and transmittance are obtained. Besides, the composite coating also possessed photoinduced hydrophilicity. Therefore, composite coated glass with the performance of low emittance, low conductivity, solar control and self-cleanness are successfully prepared.