Abstract
Properties of TiO2 Functionally Graded Material (FGM) tile that combined TiO2 and Korean kaolin (Al2Si2O5(OH)4) in a graded distribution were experimentally investigated. TiO2 is an excellent photocatalysis material, however, it does not have enough the mechanical strength. Therefore, FGMs were used as the photocatalysis materials with mechanical strength. To improve the mechanical properties, kaolin was selected as a binder. The production process of FGMs has been proposed. TiO2 FGMs were produced by progressive lamination, solid-liquid separation and mechanical expression involving filtration, mechanical compression and sintering. By this process, it is easy to control the thickness of FGMs. The results show that porosity in FGM depends on the content of TiO2. The material was found to have a bending strength of 2.5 MPa. The bending strength increases with increasing compression pressure. The results also show that these properties of FGM, such as porosity, mechanical strength, etc., can be controlled by content of TiO2 and compression pressure. Based on an optimal design of production conditions, TiO2 FGMs were developed for the nitrogen oxides (NOx) removal. NOx removal efficiency increases with increasing the content of TiO2. NOx removal efficiency was found to drop drastically at 900°C, since TiO2 changes from anatase type to rutile type at 900°C or more. It can be concluded that TiO2 FGMs developed using solid-liquid separation technique have an application to the air purification because FGMs have high NOx reduction efficiency as well as good mechanical properties.
