Papers by Author: Yoshiyuki Uchida

Abstract: Mechanical properties of TiO2-Kaolin Functionally Graded Materials (FGMs) 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 the mechanical strength sufficiently. Therefore, FGMs were used as the photocatalysis materials with mechanical strength. To improve the mechanical properties, Korean kaolin was selected as a binder. Bulk FGMs were produced by vacuum filtration and compression involving wet filtration, mechanical compression and sintering. By this process, it is easy to control the thickness of FGMs. The porosity in FGM depends on the content of TiO2. The porosity in FGM decreases with increasing pressure of the compressor. The shrinkage decreases with increasing compression pressure at all ratios of TiO2 and kaolin. The materials have almost no shrinkage at 10 MPa. The bending strength and the Young’ modulus depends on content of TiO2. The bending strength of material was found to be approximately 2.5 MPa for 10 MPa compression pressure at TiO2 side. The bending strength and the Young’ modulus increases with increasing compression pressure. These results indicate that kaolin particles are useful to improve the strength of FGM. These properties of FGM, such as porosity, shrinkage, mechanical strength, etc., can be controlled by content of TiO2 and compression pressure. Based on an optimal design of production conditions, FGMs were developed for the nitrogen oxides (NOx) removal. The NOx reduction increases with increasing compression pressure. NO of 11.7 mg/m2h was removed under present conditions. The sintering temperature ensured the optimal removal of NOx was 800 oC. After NOx removal test, the FGMs were found to be free from erosion due to photocatalysis. And kaolin particles do not interfere in photocatalysis effect of TiO2. It can be concluded that TiO2-Kaolin FGM have a possibility for application to the air purification.

Abstract: In the 21st century, the optical computation is likely to be the basic technology for processing lots of information at high speed. The aim of the present research work is to develop optical logic gates or memory chips. For this purpose, we have examined the suitability of organic nonlinear optical dye material Vanadyl-phthalocyanine (VOPc). Large single crystals of this material have been fabricated by using Molecular Beam Epitaxy (MBE) technique. The epitaxial films were formed on the substrate under optimum operating conditions. However, the epitixial growth is observed only up to a limited thickness. Above this thickness, the films become non-epitaxial, which can be improved by annealing. The reformation of the epitaxial films has been confirmed. We have also reported the effects of the environment of high temperature on the multilayered tetra-tert-butyl-Vanadyl-phthalocyanine ((t-bu)4VOPc) films, formed by Langmuir-Blodgett (LB) method. The solvent used to dissolve ((t-bu)4VOPc) was 1,2-dichloroethane. The monolayer on the surface of the water was transferred to a glass substrate by the vertical dipping method. If the multilayered stack is too thick, the molecular arrangement of the film may get disturbed. The improvement in the molecular arrangement of the LB films was examined and confirmed by measuring it’s nonlinear optical susceptibility, using Maker Fringe Method. Monolayer formation on water surface depends on the surface pressure-area isotherm. If this monolayer formation is not perfect, multiplayer stacks cannot be formed. The molecular films were aligned almost perpendicular to the substrate, as estimated from the limiting molecular area of surface pressure-area isotherm. The molecular organization of the monolayer on the substrate and the molecular structure of the multilayered ((t-bu)4VOPc) films are discussed.