Prepartion Of Self-cleaning Fluorocarbon Aluminum Coating With Nano TiO₂at Low-temperature

The beginning of researching fever for photocatalyst in the catalytic field originates with an important discover by Fujishima in1972of photocatalytic splitting of water on titanium dioxide electrodes. The titanium dioxide has been the main research object for the advantages, such as good photocatalytic activity by degradating the pollutants under the ultraviolet irradiance, easy to get, and stable without secondary pollutants to the environment. So it has been regarded as the most effective photocatalyst to realize the in the future.The fluorocarbon aluminum has been widely used as the building materials for the character of light quality, good rigidity and high strength. However it is difficult to maintain the aesthetic characteristics for the badly society pollutants witch promotes researchers to developing a new kind of fluorocarbon aluminum with the ability of self-cleaning. As so far, the research of titanium dioxide coating on the fluorocarbon aluminum is limited, so the further studies are essential.The preparation process of TiO2sol and properties of the self-cleaning fluorocarbon aluminum witch coated with the sol by dip-coating technique on the surface were systematically studied. In this study, the butyl titanate and fluorocarbon aluminum were chosen as precursor material and basic substance. The anatase TiO2sol was synthesized at the condition of water bathing by improving sol-gel method and the dip-coating method was used to prepare films on the fluorocarbon aluminum surface. The effects of process parameters such as water amount, pH value, water bathing temperature and time on the properties of sol and self-cleaning fluorocarbon aluminum coatings were studied. The particle size of sol was analyzed by the laser particle size, the crystal structure of TiO2particle was characterized by X-ray diffract meter and Fourier transform infrared spectrometer, the surface morphology and optical absorption properties were characterized by scanning electron microscope and ultraviolet-visible spectrometer respectively. The hydrophilic and photocatalytic properties of the self-cleaning fluorocarbon aluminum were evaluated through degrading the methylence blue solution under the UV irradiation. The results indicated that the propriety of the sol was stable and the hydrolysis degree of butyl titanate gradually intends to be completed with the increasing of water amount and decreasing of pH value. When the mol ratio of butyl titanate and water is1:120with pH value of2, the butyl titanate was completely hydrolyzed and the TiO2sol with good anatase crystal structure was stable so that is can be place for long time. And the butyl titanate was all hydrolysis after bathing, besides, the crystalline degree improved with the increasing of bathing temperature and time witch show the time-temperature equivalence effect. The anatase TiO2sol after bathing for8h at80℃was used to prepare the self-cleaning fluorocarbon aluminum.The results showed that the coatings on the surface of self-cleaning fluorocarbon aluminum processed a dense surface; the particle size was fine and uniform and about10-20nm. A strong absorption property was reflected around the360nm and the light response range was also improved by the red shift of the absorption edge. Comparing to the fluorocarbon aluminum the water contact angle of the self-cleaning fluorocarbon was less than10degrees instead of70degrees after UV irradiating for3h witch showed a super hydrophilic property. And the water contact angle kept decreasing to0degree with the increasing illumination time. In addition, the photocatalytic activity of the self-cleaning fluorocarbon aluminum was evaluated by the degradation of methylence blue solution under UV irradiation.The results illustrated that the self-cleaning fluorocarbon aluminum showed a good photocatalytic activity, and the photocatalytic activity was improved with the increasing bathing time. The degradation of self-cleaning fluorocarbon aluminun prepared by the TiO2sol without water bathing was about20.9%, on the other hand, the degradation was improved to about64.02%and72.1%respectively of witch prepared by the TiO2sol with water bathing for4h and8h respectively at80℃.