Takao Yakou

Control of intermetallic compound layers at interface between steel and aluminum by diffusion-treatment

Abstract The toughening of Fe–Al intermetallic compound coating formed by aluminizing of carbon steel was investigated. The growth mechanism, morphology and mechanical properties of Fe–Al intermetallic compound layers on the surface of carbon steel were systematically evaluated for specimens diffused at temperatures ranging from 873 to 1323 K after hot dip aluminizing. Fe2Al5 was mainly formed on the specimen surfaces at the usual diffusion temperatures from 873 to 923 K. However, FeAl and Fe3Al layers having relatively high fracture resistance and oxidation resistance properties were preferentially formed in the specimens diffused at temperatures greater than 1273 K. The activation energies required for the growth of the FeAl and Fe3Al layers were QFeAl=180 and QFe3Al=260 kJ mol−1, respectively. It was identified that the formation and growth of Fe–Al intermetallic compound layers is controlled by the diffusion of Fe atoms into the intermetallic compound layers.

Effect of annual rings on abrasive wear property of wood

In this study we investigated the abrasive wear property of Douglas fir (Pseudostuga menziesii Franco) on abrasive paper using test specimens with various dimensions and annual ring widths. The effect of the annual rings on the abrasive wear property of Douglas fir was clarified from the relation with the compression strength of the wood specimens. The dispersion of the wear coefficient, which was calculated as the wear volume divided by the friction distance and the load applied to the friction surface, varied when there were fewer than approximately three annual rings in the specimen, as did the compression strength. As clarified from these results, it was found that the effect of the annual rings on the abrasive wear and compression properties of Douglas fir is closely related to the earlywood/ latewood ratio.

Two-body and three-body abrasive wear properties of katsura wood

Two-body and three-body abrasive wear tests of katsura wood were carried out using abrasive paper and moving abrasive grains, respectively. The two-body and three-body abrasive wear properties were investigated and compared. The wear rate of two-body abrasive wear was two orders of magnitude larger than that of three-body abrasive wear. Moreover, two-body abrasive wear of katsura wood increased with higher applied surface pressure, whereas three-body abrasive wear did not always depend on the applied surface pressure. Based on these results and observation of the wear surface profiles, it is suggested that two-body abrasive wear is more affected by yield stress and surface microstructure, and three-body abrasive wear is more affected by the cutting action of moving abrasive grains. Furthermore, during wear tests with different abrasive grain sizes, critical grain size effects of two-body abrasive wear were observed at low applied surface pressures but not at high applied surface pressures. The critical grain size effects of three-body abrasive wear were observed at both low and high applied surface pressures.

Fundamental Characteristics of Grooving Aiming at Reduction of Kerf Loss Using an Ultrafine Wire Tool

Thinning of silicon wafers and reduction of kerf loss can minimize the manufacturing costs of semiconductor products. Currently, the volume of kerf loss is about the same as the volume of the wafer itself. Therefore, we study slicing techniques for silicon wafers that result in reduced kerf loss by using an ultrafine wire tool and fine abrasive grains. As a first step, grooving characteristics using an ultrafine tungsten wire tool and fine abrasive grains are investigated in this paper. A borosilicate glass is used as the work material. The main conclusions are as follows: Precision machining using ultrafine wire tool is possible and the kerf loss decreases because the groove width decreases. However, a larger diameter of the wire tool results in a deeper groove. A faster relative speed produces a shorter wire tool lifetime, but a deeper groove. To supply enough abrasive grains to the machined portion, it is necessary to use abrasive grains having a suitable particle size for the specific diameter of the ultrafine wire tool.

Anodic Dissolution of Spheroidal Graphite Cast Iron with Different Pearlite Areas in Sulfuric Acid Solutions

The rate equation of anodic dissolution reaction of spheroidal graphite cast iron in sulfuric acid solutions at 298 K has been studied. The cast irons have different areas of pearlite. The anodic Tafel slope of 0.043 V decade−1 and the reaction order with respect to the hydroxyl ion activity of 1 are obtained by the linear potential sweep technique. The anodic current density does not depend on the area of pearlite. There is no difference in the anodic dissolution reaction mechanisms between pure iron and spheroidal graphite cast iron. The anodic current density of the cast iron is higher than that of the pure iron.

Microgrooving Using an Ultrafine Wire Tool

We examined the slicing technique of silicon wafers with little kerf loss using an ultrafine wire tool. As the first step, we performed microgrooving with an ultrafine wire tool. The thinning of the wafer and the decrease in kerf loss can minimize production costs. We discuss the strength characteristics and the microgrooving performance of the ultrafine wire tool. The main results are as follows. The relative velocity greatly affects the grooving properties. The ultrafine wire tool easily breaks when the relative speed is high. When the ultrafine wire tool and abrasives with large diameter grains are used, the ultrafine wire easily breaks and chipping in the work material easily occurs; furthermore, the ultrafine wire strays.

Relation between Sensory Evaluation of the Grasping Cylinder with Lifting Hand and the Arch of Hand.

In order to realize the grasping mechanism of hand which grasps cylinder with lifting hand, the relationships between the optimum diameter of grasping cylinder and arches formed by fingers and palm was investigated. The optimum grasping diameter of the lifting hand was approximately 30 mm at no weighted condition, the diameter increase with increasing the lifting weight of pipes, then saturated about 40 mm at 30 N. It was found that the arches formed by a palm-forc fingers except for a thumb was more closely connected with the optimum grasping diameter than the arches formed by a thumb-a forefinger. From these results, in view of the arch formation, the grasping mechanism with lifting hand and its weight dependence was discussed.

Relationship Between Handle Size of Milling Machine and Comfortableness to Handle Operation.

In order to clarify the relationship between handle size of milling machine and comfortableness to handle operation, sensory evaluation test and the measurement of cutting force and contact pattern between hand and handle have been performed. It was proved that the handles of larger sizes were evaluated as more comfortable, the subjects operating large handle with both hands could operate with large cutting force and short operation time, and the subjects operating handle with one hand could not rotate continuously the handle. It was thought that the comfortableness to handle operation depends on the large contact area between hand and handle and small load on hand.

Bonding test of thin grinding wheels

Bonding test of thin grinding wheels has been performed, using bit type testing machine. Bit displacement and torque were inversely proportional to the bonding grade of wheels, and were more closely connected with the bond contents. The torque needed to pulling out a grain was obtained as a function of the amount of bond contents per one grain. It was found that, the higher the bonding grade wheel, grains were more breakable than the lower one.

Modelling and vibration characteristics of human arm system

This paper describes modelling and analysis of a human hand-arm-shoulder system. When a person works or plays a sport requiring the use of a tool, a force is transmitted from the tool to the hand-arm system. Therefore, a dynamically coupled model must be utilized for the analysis of a tool-hand-arm-shoulder system. The shoulder has three degrees of freedom, two rotary motions and one torsional motion, the elbow has one bending motion, and the wrist has two bending motions and one torsional motion. In total, the system has seven degrees of freedom. Muscle can pull bones but not push them, so a system with seven degrees of freedom consists of fourteen muscles. Here, we consider the vibration model with 3 DOF of the shoulder and 1 DOF of the elbow to calculate the eigenfrequencies and its vibration modes. The authors examined two cases : one case in which the hand is free, and the other in which the hand is vibrated by an oscillator. The experimental results show good agreement with the calculated data.