This paper addresses analysis of mode I and II crack tip singular stress fields in single crystal silicon and 3C-SiC used as MEMS mechanical structures. Fundamental solutions of anisotropic elastic fields of isolated dislocations obtained by Eshelby, Hirth and Lothe were used to derive the closed form crack tip singular stress fields. It was concluded that three elastic stiffness coefficients of diamond lattice structure have important role to control the crack tip singular stress fields, and maximum hoop stress for mixed mode proposed by Erdogan and Sih.

In recent years, the usage of adhesives in the joints of automobile bodies has been expected. Researches on estimating fatigue life are necessary to establish design criteria for adhesive joints. If the fatigue life of bonded joints can be estimated based on the evaluation of fatigue life of a simple-shaped specimen, it will lead to an increase in the efficiency for the design and development stage and cost reduction. In previous researches, it was clarified that interfacial failure was restrained by treating surface of the adherent, and the emergence of low adhesive strength was restrained by the cohesive failure rate at over 40 %. In case of cohesive failure, the strength of bonded joint depends on the strength of an adhesive, allowing the fatigue characteristics of the adhesion specimen to be reproduced by using the fatigue characteristics of the adhesive bulk specimen. In this study, FEM analysis was carried out in order to identify the location of stress concentration and to clarify the relationship between stress value at stress concentration zone and the load value within the adhesive layer of an adhesive specimen. The fatigue test of the adhesive bulk specimen and the adhesive specimens was carried out and the crack initiation life of the adhesive specimen was estimated by converting the stress axes of S-N curve using the analysis results. As a result, in T-peel adhesive specimen, the stress range at crack initiation cycle of the adhesive specimen has been estimated to be higher than the stress range at the same cycle of the adhesive bulk specimen by using average stress at the position where the stress averaged in the thickness direction of the adhesive layer is maximum as a representative value (method 1) in both the maximum principal stress criteria and the Mises stress criteria, and the estimated fatigue life could be conservative. In overlapping adhesive specimen, the stress range at crack initiation cycle of the adhesive specimen has been estimated to be excessively higher than the stress range at the same cycle of the adhesive bulk specimen by using method 1 in both the maximum principal stress criteria and the Mises stress criteria. Compared to method 1, the stress range at crack initiation cycle of the adhesive specimen has been estimated to be closer than the stress range at the same cycle of the adhesive bulk specimen by using average stress averaged in the thickness direction of the adhesive layer at the nodal position where maximum stress is generated (method 2).

In case of multi-material hat-shaped members, the bonding strength between dissimilar materials has a great influence on the bending stiffness of the entire structural member, thus it is an important issue to secure the bonding strength between dissimilar materials. In this study, in order to develop a multi-material hat-shaped member with high specific strength and high specific stiffness, the effects of surface treatment for Mg Alloy and hot-melt adhesive film on the bonding strength were clarified from tensile shear tests of thermally welded CFRTP and Mg alloy. In addition, three-point bending tests were conducted on multi-material hat-shaped members that were fabricated by press-injection hybrid molding. The effects of the surface treatment for Mg alloy and hot-melt adhesive film on the bending properties of the hat-shaped members were clarified. When CFRTP and Mg alloy were heat welded, the use of chemical-treated Mg alloy showed higher bonding strength than that of untreated Mg alloy; and the use of hot-melt adhesive film showed even higher bonding strength. In the three-point bending test of the multi-material hat-shaped member, when stacked CFRTP laminate and Mg alloy were used as the surface material, the use of chemical-treated Mg alloy showed higher maximum load and stiffness. Meanwhile when the hot-melt adhesive film at the bonding interface between the CFRTP laminate and the Mg alloy was used, the highest maximum load and stiffness were obtained. However, as there was no significant difference in the maximum load and stiffness between untreated and chemical-treated Mg alloy when the hot-melt adhesive film was used, chemical-treatment for Mg alloy is not necessary.

We conducted a gas permeation test on polyether ether ketone (PEEK), polyimide (PI), polycarbonate (PC), polypropylene (PP), and cellophane (PT) membranes at room temperature using Gas Transmission-rate Measuring Equipment (GTME) designed by ourselves and determined their permeability coefficient. Among the five types of test pieces, PP shows the largest hydrogen permeability coefficient of 2.24×10^-15 [mol / m･s･Pa] and PT does the smallest one of 5.78×10^-17 [mol / m･s･Pa]. All of the permeability coefficients are almost the same as the results of other researchers. Generally, the hydrogen permeability coefficient is considered to be a parameter that does not depend on the film thickness. The measurements of PEEK and PI with different thicknesses showed that the coefficients were affected by the film thickness. Since the state of the polymer chains in the thickness direction also affects the diffusion as the film thickness increases, in such a case, it is considered effective to add the hydrogen permeation amount to the evaluation parameters. The hydrogen permeability coefficient of PEEK and PI increased with increasing temperature in the temperature range of this experiment. In particular, PEEK with a glass transition temperature of 140°C to 220°C changed the tendency of the hydrogen permeability coefficient in this temperature range, because the diffusion characteristics of hydrogen are improved by the increase in free volume caused by the initiation of Micro Brownian motion in the molecular chain of the non-crystalline part.

The fabrication of nano-sized zeolites with an average size of 200 to 400 nm was attempted by the bottom-up process such as the hydrothermal technique, in which zeolite nucleation and crystal growth were controlled during the hydrothermal synthesis. Effect of hydrothermal parameters like synthetic temperatures, holding times, and compositions of starting materials on the microstructures of zeolites were mainly investigated. In addition, influence of aging of mixture of starting materials at room temperature before hydrothermal treatments was examined. In this study, in special, homogeneous zeolite A (LTA type structure) nanocrystals without an average size less than 100 nm and coarse zeolites over 500 nm were successfully synthesized by the present bottom-up process under optimum hydrothermal conditions at 60 °C for 3 hr after aging at room temperature.

Rice husks are a by-product of rice production, and 2 million tons are emitted annually in Japan. However, its use is limited to low value-added methods, and effective utilization methods are not sufficiently studied. On the other hand, gramineous plants are silicic acid-accumulating plants that have the characteristic of selectively absorbing silica in soil and storing it in the body. Therefore, about 20% of the composition of rice husks is composed of silica. Since the rice husk ash obtained by burning the organic component of the rice husk contains a large amount of silica, it is expected to be used as a Si source. In this study, we succeeded in producing a cured product by a geopolymer reaction by synthesizing an alkaline aqueous solution of silicate using rice husk ash as raw material and adding metakaolin to it. In addition, a geopolymer porous body was obtained by adding Si powder as a foaming agent and introducing pores by hydrogen foaming reaction into the cured body. Furthermore, it was clarified that by adding a surfactant as a bubble stabilizer in addition to Si powder, defoaming of generated hydrogen bubbles can be suppressed and pores can be made fine and uniform. As a result of measuring the heat insulating performance of the geopolymer porous body, it was possible to introduce a large number of pores of 0.5 to 1, 5 to 100 µm by adjusting the amount of Si powder and surfactant added. Furthermore, it was clarified that the porous body with many fine pores shows better heat insulation performance.

Gypsum board is widely used as an excellent building material, but in recent years the amount of waste has been increasing due to the rebuilding of buildings, so it is required to establish a new reuse method. The purpose of this study was to develop a water purification material that can remove phosphorus and organic matters at the same time using a waste gypsum board. In order to improve the shape retention of the gypsum board in water, polyvinyl butyral (PVB) or silica coating was applied to the gypsum board, and the effect of the type of coating materials on the phosphorus and organic substances removal abilities was investigated. After coating, samples were immersed in a sodium carbonate aqueous solution to precipitate calcium carbonate on the sample surface, and then immersed in activated sludge for 5 days to carry microorganisms on the sample surface. Phosphorus and organic matters could be removed with both silica and PVB coated samples. However, when the silica coating was applied, the calcium carbonate layer on the surface was peeled off after the removal experiment, and a decrease in the phosphorus removal ability after carrying microorganisms was observed as compared with the case of the PVB coating. On the other hand, for the PVB-coated sample, no peeling of the sample surface was observed after removal of phosphorus and organic matters, and the decrease in phosphorus removal ability after carrying microorganisms was small. Therefore, PVB coating is considered to be effective in reusing waste gypsum board as a water purification material.

The effect of the microstructure of a microorganism-supported alumina porous body on the organic matter removal ability in water was investigated. Alumina porous bodies with different pore diameters and pore volumes were prepared by changing the particle size and addition ratio of pore-forming agents. Microorganisms were supported by immersing the porous alumina body in a culture solution containing yeast, lactic-acid bacilli and bacillus natto, or activated sludge for 5 days, and the effect of the kind of microorganism species supported on the porous alumina body on the organic matter removal ability was also investigated. The organic matter removal ability was evaluated by immersing the microorganism-supported porous alumina in model sewage containing glycine and glucose so that the initial COD value was 180 ppm, and measuring the change in the COD value. It was found that the COD decreasing ratio was not affected by the pore size of the alumina porous body regardless of the microbial species, but it increased with increasing pore volume. In addition, it was also confirmed that the COD decreasing ratio was higher when the microorganisms derived from activated sludge were supported than the microorganisms derived from the culture solution.

Transparent hygroscopic composite films using 4A zeolite particles with a primary particle size of 50 nm, which is smaller than the wavelength of visible light, with the ability to absorb moisture as a filler were fabricated. Nano-sized 4A zeolite has the following problems as a filler of resin. The nano-sized particles easily agglomerate and it is particularly difficult to disperse into a hydrophobic resin. Therefore, in order to improve dispersibility, the surface of nano-size 4A zeolite was modified by using surface modifiers. Furthermore, in this work, it was found that the surface modifiers with different refractive indices resulted in mixtures of zeolite and resin with different optical properties. In other words, the use of a surface modifier with a refractive index close to that of the resin was found to yield a transparent hygroscopic film. Finally, a transparent resin sheet with zeolite content of 30wt% and the haze of less than 30% was fabricated. The dispersibility and transparency were improved by treating zeolite with a primary particle size of 50 nm by a surface modifier of high refractive index, and mixing it with a resin of low refractive index.