Study Of TiO₂ Film On Enamel Substrate

Nanometer-sized titanium dioxide has good photo-catalyzed performance. It has been widely applied in degradation of organic pollutant. Recently, a lot of scientific researches about TiO₂ film have been carried out in many fields of inorganic and organic materials. These researches mostly focus on ceramics, glass, chemical fiber and metal base etc. There is lack of relevant researches about enamel substrate. In this thesis, the TiO₂ film was fabricated successfully on enamel substrate by the sol-gel method. Firstly, the research work of influencing factor about preparation of sol solution was studied. Secondly, the research work focuses on the transformation mechanism of crystal phase in heat processing and the analysis of TiO₂ film's surface microstructure. At last, using ultraviolet spectrophotometric method tests the photo-catalyzed performance of the TiO₂ film on enamel substrate.The surface cleaning of enamel substrate is the key for coating operation in this experiment. In order to achieve a good adherence, all basic substrate must be treated by acid washing, ultrasonic cleaning and finally rinsing by de-ionized water. In the preparation of sol solution, a lot of factors, for example: water content, ethanol content, pH value, depressant and hydrolyzed temperature etc. will influence the gelatin time. Through many tests, we confirms that the sol mixture ratio was Ti(OC₄H₉)₄: H₂O: C₂H₅OH: HNO₃: AcAc= 1: 2: 18: 0.2: 0.5. Then, the TiO₂ film was coated on enamel substrate by using dipping-lifting method.The heat processing is also very important for the formation of crystal phase, surface microstructure of the TiO₂ film and the film's photo-catalyzed performance. With the help of XRD TG-DSC and SEM instruments, we analyze the formation of crystal phase and surface microstructure of the TiO₂ film in the experiments. According to the experiment data, the crystal phase is transforming gradually as the temperature grows. Between 600℃ to 700℃, the crystal phase of TiO₂ is transforming from anatase to rutile. The crystal phase of TiO₂ is still anatase when PEG was put in at 500℃. According to the data of SEM, PEG will cause the multi-hole structure of the TiO₂ film. When molecular weight of PEG increases, the amount of multi-hole structure willincrease and the aperture will expand at 500 ℃Taking methyl orange solution with 10mg/L concentration as imitated agent, we analyze the photo-catalyzed efficiency of TiO₂ film under exposure of 365nm ultraviolet light. The result indicates that the enamel substrate without TiO₂ film has lower photo-catalyzed performance. At the same heat processing temperature, the photo-catalyzed efficiency of TiO₂ film is enhanced with the increasing of TiO₂ layer. When PEG added into sol, photo-catalyzed efficiency of the TiO₂ film is increased because the structure of film is changed by PEG. The photo-catalyzed efficiency of the film fired at 500℃ is lower than that of the film at 450℃ temperature, but still higher than that of the enamel substrate without TiO₂ film.