Isao Fukumoto

Fabrication and Flexural Properties of Bagasse Fiber Reinforced Biodegradable Composites

Biodegradable composites made from bagasse fiber and biodegradable resin were fabricated and the flexural properties of the composites investigated in terms of the effects of fiber length, fiber volume fraction, and different alkali treatments of the bagasse fibers. The flexural properties of the composites increased with the increase in fiber length but decreased below the critical fiber length. The flexural properties increased with the increase in fiber volume fraction. The scanning electron microscope (SEM) micrographs showed that compression of the cellulose structure of bagasse fiber after preparation could have caused enhancement in the flexural properties. Furthermore, when comparing the effects of different alkali treatments of the bagasse fibers, maximum improvement in the flexural properties was observed for the 1% NaOH solution treated fiber composites. After alkali treatment, fibrillation occurred and the surface of the treated fibers became finer; this could contribute to improvement in the fiber‐matrix adhesion and result in enhancing the flexural properties.

Improvement of ground surface roughness in Al-Si alloys

Abstract Al-Si alloys are difficult materials to cut, having nodules of silicon (hard phase) distributed at random over a matrix of aluminium (soft phase). These alloys having a silicon content over 11%, to include eutectic and hypereutectic alloys, have proven to be very hard to wear down, making them potentially useful in precision-engineered instruments and machines and for pistons in automobiles. However, the grinding process used to give these articles a highly polished surface finish must be considered owing to the great difficulty in grinding these types of alloys. Al-Si alloys containing 11–26 wt.% Si were used in this study to ascertain the grinding characteristics of these alloys over a range of differing parameters. Different grinding wheels and different fluids were used in the grinding process to determine the most efficient method of grinding Al-Si alloys. Power spectrum analysis was used to determine the roughness of the materials after the grinding process, and an autoregression model was adapted to the power spectrum analysis data to calculate roughness curves for each of the alloys. As a result of this study it was found that a grinding wheel C46JmV with an emulsion-type grinding fluid-provided smoother surfaces for Al-Si alloys.

Prediction of Flexural Modulus of the Biodegradable Composites Made from Bamboo and Kenaf Fibers

Biocomposites made from bamboo, kenaf and biodegradable resin were fabricated with a press forming. The biodegradable resin used was a corn starch based resin. The effect of fiber content on flexural modulus was investigated. The Young’s modulus of each fiber was measured to predict the flexural modulus in the composites. The flexural modulus was predicted by Cox model, which incorporated the effect of the fiber compression. The flexural modulus increased with increasing the fiber content. The flexural modulus difference between experimental and calculation was large in bamboo. This is because Young’s modulus in bamboo fiber was estimated considerably lower than the actual modulus due to partial breakage bamboo structure during fiber tensile test. Moreover, the flexural modulus in the unidirectional fiber composite made a good agreement with the predicted. However, the flexural modulus in the fiber cross ply composites was considerably lower than predicted because the less fibers movement during hot pressing made the fibers less wetting and resulted in the resin segregation.

Grain Boundary Migration Simulation by Vertex Dynamics in the Weld Metal of an Austenitic Stainless Steel.

The weld metal of stainless steel SUS310S was investigated for the purpose of making clear the direction of grain boundary migration. Using a vertex dynamics model, we calculated the transient process of the grain growth in the base metal and grain boundary migration in the weld metal. The results was compared with the observation of the grain boundary migration in the weld metal. The results are obtained as follows.(1) A frictional coefficient for grain boundary migration is assumed to be proportional to the third power of the grain boundary length. The grain growth rate calculated using this coefficient agrees with the quarter power of growth time shown in our experiment.(2) The distribution of numbers of edges surrounding a grain is apt to be universal and independent of the initial conditions and the vertex dynamics model.(3) The moving direction of the grain boundary triple junctions calculated in the weld metal has good agreement with the experiment results.

Grain Boundary Migration of the Surface in the Weld Metal of an Austenitic Stainless Steel.

The grain boundary migration in the surface of the weld of an austenitic stainless steel was observed. In the cross section shape of the grain boundary groove, the thermal grooving theory in the surface based on the surface flow was compared to the experimental results. Furthermore, the relationship between the angle which is the plane of the solidification grain boundary to the surface plane and the amount of the grain boundary migration were discussed. The obtained results are as follows.The relationship between the cross section shape of the grain boundary groove which migrated in the surface of the weld metal and the direction of the grain boundary migration is good agreement with those of thermal grooving theory. That is, the plane of the grain boundary migrates to approach to be a right angle to the surface plane.The amount of the grain boundary migration increases with increase of the angle of the solidification grain boundary to a right angle of the surface. This reason is why the plane of the grain boundary which has higher angle to a right angle of the surface is able to migrate with less friction force than that which has lower.