Koichi Kaizu

Development of the Green Composite Consists of Woodchips, Bamboo Fibers and Biodegradable

From the viewpoint of the effective utilization of natural resources, the green composite which is produced by solidifying woodchips has been developed[1][2][3]. However, since this composite was solidified by the compressive load without the binder, the composite was very brittle and had no water resistance [4]. In this study, to improve these defects, the biodegradable resin is used as an adhesive and bamboo fibers are used as reinforced fibers. By using woodchips with two kinds of the particle size, bamboo fibers with three kinds of the length and a biodegradable adhesive, several kinds of specimens changed those mixing ratio were produced. The composite consists of the ingredients which are friendly to the environment. By the four-point bending test and Charpy impact test, the bending strength and impact strength of the composites were examined. From the experimental results, it was found that the high bending strength and high energy absorption were obtained in case where woodchips with the small particle size and long bamboo fibers were used. The proposed composite has the high strength, and the practical application is also possible.

Crack Growth Characteristics Evaluation Method in Ceramics Based on DT Technique

A new method to evaluate the relationship between stress intensity factor KI and crack growth rate V of ceramics which is based on Double-Torsion (DT) technique was proposed. Materials were soda-lime glass, glass ceramics and alumina ceramics. Plate type DT specimens were prepared, and rectangular section guide groove was introduced in the upper surface of specimen. As a crack propagation test, a constant loading rate test was performed. Furthermore, a crack growth behavior was monitored by a compliance method. As the results, it was found that the clack growth behavior can be detected with high accuracy by using the proposed method. And it was confirmed that crack growth characteristic over wide range of crack growth rate can be evaluated by single experiment. Furthermore, since the method is based on a simple measurement system, it is considered that the method has a good availability for KI-V evaluation in ceramics.

High-Strength Porous Ceramics Produced by Recycling Glass Fibers in Waste GFRP

Ceramics, Composite Material, GFRP, Clay, Recycling, Bending strength Abstract In this study, as the effective recycling technique for the waste GFRP, the process for the producing the porous glass fiber reinforced ceramics by firing the mixture of the clay and the crushed waste GFRP was proposed. The proposed recycling technique for the waste GFRP enables to produce various ceramics parts by effectively reusing the glass fibers included in the waste GFRP as well as to dispose injurious GFRP radically. By changing the mixing ratio of the waste GFRP and clay, and by firing the mixture at some temperatures, several kinds of ceramics specimens (tiles) were produced. The microstructure of each specimen was observed using the SEM and the microscope, and then water absorption and the bending strength of the specimens were examined in detail by comparison with those of specimens without the glass fiber. From those results, it was confirmed that the high-strength porous glass fiber reinforced ceramics could be produced by our proposed process.

Evaluation of KI-V Relation in Ceramics by Using Dt Technique (Crack Length Measurement by Using Compliance Method)

Double torsion (DT) technique has been widely used as crack growth test for brittle materials. The technique is known to convenient for that the applied stress intensity factor, K I , is independent of the crack length, specimen and loading geometries are simple, and the slow crack growth data can be obtained using the load relaxation method. However it is difficult to obtain accurate data by the relaxation method because of extraneous relaxations by thermal expansion and the lack of stiffness in test devices. So, in this study, the new method to estimate the crack growth of ceramics will be suggested by combining a compliance method with a grid pattern film method[1].