Design And Preparation Of TiO₂Self-Cleaning Low Emissivity Composite Films

Low emissivity film plays a highly efficient thermal insulation effect for having high visible light transmittance and infrared reflectance, while TiO2coated glass can implement self-cleaning for having a good photocatalytic performance and hydrophilicity performance. when low emissivity film and TiO2film were prepared on the two sides of the glass, the glass can realize heat insulation and self-cleaning function at the same time.Air/TiO2(100nm)/Glass/TiO2(30nm)/Ag(15nm)/Ti(1nm)/TiO2(30nm)/Air was the structure of TiO2self-cleaning low emissivity composite film which was designed by using TFCalc software, and the result was analyzed.The multilayer structure of TiO2/Ag/Ti/TiO2low emissivity films were designed according to the basic principles of low emissivity films, and we used TFCalc software to design on the thickness of Ag film and TiO2film, coated glass had high transmittance at visible center wavelength of550nm when TiO2film thickness of30nm, Ag film thickness of15nm. TiO2/Ag/Ti/TiO2low emissivity films were prepared by electron beam evaporation method according to the results of simulation, low-emissivity glass had high transmittance in visible range when films with Ag thickness of15nm, and W70which is the width of the wavelength of visible transmittance more than70%closed to330nm, infrared emissivity only0.06, while coated glass with Ag thickness of10nm or20nm had lower visible transmittance. The critical thickness of Ag film to form a continuous film was about15nm by the comprehensive analysis of thin film resistance combined with the observation of atomic force microscope and other methods. According to the effect of Ag film thickness on the optical properties of multilayer films, multilayer films can obtain the best low radiation effect when the reflective layer just form a continuous film.Effect of different thickness of Ag film and TiO2film on the optical properties of TiO2/Al/TiO2multilayer low emissivity films were simulated by using TFCalc software, and prepared by electron beam evaporation technology. Through the comprehensive analysis of the theoretical simulation results and experimental results, we deemed that Al was easily oxidized to aluminum oxide in the coating process, changing the structure of the films, which made a large deviation between the experiment result and the design result. TiO2film was prepared on glass by electron beam evaporation method, and we studied on the effect of the heat treatment technology on the structure and properties of TiO2film. After heat treatment at450℃, TiO2film transform formed amorphous to crystalline anatase, average transmittance of the visible range reduced, forbidden band width became smaller, but the hydrophilic improved, and photocatalytic degradation speed increased after UV irradiation40min.