Preparation Of Nano ATO-TiO₂Composite Materials And Their Application In Thermal Insulation And Self-cleaning

As a kind of n-type semiconductor, antimony doped tin oxide (ATO) is an excellent transparent conductive materials that can be prepared at a low cost, While TiO2has a good performance in pigments and possesses high photocatalytic activity and superhydrophilic properties. If some proper methods could be adopted to obtain a newly transparent insulated and self-cleaning material, which presents an outstanding transmittance and good thermal insulation property, at the same time it has self-cleaning and antibacterium effect. As a result, they could be widely applicated in the fileld of energy conservation and environmental protection. However, a feasible way to combine the ATO with TiO2together would be a key determinant problem. Tranditional ways such as magnetron sputtering deposition and chemical vapor deposition are not suitable for mass production due to their high cost. Conversely, wet chemical deposition could produce uniform coating of excellent properties with a low cost. Because of these, this kind of preparing way could be readily available for widespread use and would be certain to have a significant future.Ordinary nano-TiO2powder has the problem of wide energy gap and narrow light response. To overcome these, this article take suitable doping treatment, preparing Zn-doped, Fe-doped, N-doped, Zn-N-co-doped, Fe-N co-doped nano TiO2powder through sol-gel. XRD results shows that all the doping elements enter into the TiO2crystal lattice as replace atom and would not produce new phase. SEM results illustrates that both the Zn-doped and N-doped nano TiO2particles are very small and well-distributed. By contrast, the Fe-doped sample possess a special flocculent structure, the Zn-N-co-doped sample only has part of big particles, whilst the Fe-N co-doped sample owns many huge ones. Compared to pure Ti02,nano TiO2Doped with single element(Fe> Zn or N) see an upward trend in photocatalytic activities, while co-doped samples(Fe-N or Zn-N) show an opposite trend. The N-doped TiO2displays the highest reaction rate constant, peaking at22.11×10-3min-1 when the doping content is1%and calcined at500℃.Nano antimony doped tin oxide (ATO) particles has been sythesised through Hydrolysis precipitation method. Its phase、morphology and optical properties are separately characterized by the change of reaction temperature, pH value and calcined temperature. XRD results show that Sb enters into the SnO2crystal lattice as ionic species, substituting the Sn ion partly and forming a solid solution without producing new phase. As the react conditions change, the unit cell volume would show the same variation tendency with that of mean grain size, but display different variation tendency comparing to that of Lattice distortion. when the reaction temperature is60℃, pH=6and calcine at600℃, The prepared ATO powder shows fine grain size and high crystallinity and suitable property for the prepation of slurry.The preparation process of well dispersive TiO2slurry was studied by single-factor experimental method. The results reveal that the best dispersion process is:adding FS-02to the slurry with a mass percentage of10%. By then, adjusting the slurry pH to about5. and stiring for3h with speed of6000r/min, Finally, treating under ultrasonic dispersion for15min. The well dispersive ATO slurry was also prepared, it is found that the best dispersion condition is:adding0.25g FS-02to the slurry and adjusting the slurry pH to about8. The as-prepared TiO2or ATO slurry can maintain for a long time without evident sedimentation.The ATO/TiO2composite film was sythesised via wet chemical deposition as follows:At one stage, The Waterborne polyurethane/ATO/TiO2composite coating was prepared. After that, the ATO/TiO2coatings were successfully deposited on glass substrate via dip-coating method. Finally, the mechanical, optical, thermal and photocatalytic properties of the glass with different mass ratio of ATO/TiO2were studied. It is proposed that the best ATO/TiO2mass ratio is2/3. Under this condition, the adhesive force of the coating reaches0-level and the pencil hardness is2H, the thickness of the film is about3.5μm and the water absorption is just below0.02%. The film also has good optical properties, with average transmittance of about55%in visible light region while only under10%in infrared region. It possess good thermal insulation property as well as the self-cleaning activity.Another way to prepare the ATO/TiO2composite film is the sol-gel-dip-coating process. Firstly, how the content of Sb and the number of film layers impact the thermal insulation properties of ATO coating was studied. It is proposed that the sample of mass percentage of10%Sb and adhere6layers of ATO coating would show the excellent heating insulation property. After that, the morphology, optical, thermal and photocatalytic properties of the glass with different number layers of ATO/TiO2film were studied, it is found that the A4T4shows the best comprehensive properties. Where the coating cut off the infrared light to90%. And it also has good thermal insulation property as well as the photocalytic activity.