Papers by Author: Kenji Ikeuchi

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Authors: Makoto Takahashi, Kenji Ikeuchi
Abstract: When a voltage in the direction opposite to that for anodic bonding is applied to an anodically-bonded joint of glass whose alkali ion content is substituted by silver, silver precipitates of peculiar morphology form in the glass adjacent to the joint interface. In order to acquire knowledge about factors that control the configuration of the precipitates, effects of bonding time of the joints and application temperature of the reverse voltage on morphology of the precipitates were investigated. Shortening of the bonding time and increase of the application temperature of the reverse voltage cause decrease of the size of precipitates, and these effects were explained from formation frequency of current paths in the Ag+ depletion layer with penetration of Ag+ ions into the layer.
Authors: Shinji Koyama, Makoto Takahashi, Kenji Ikeuchi
Abstract: The bond interface of a TLP (Transient Liquid Phase) bonded tin has been observed with a TEM to investigate the effect of the liquid phase on the behavior of the superficial oxide film at the interface during the bonding process. In the solid-state-diffusion bonded joint without filler, abundant oxide inclusions were observed to be distributed within a region of a few 100 nm widths along the bond interface. In comparison with this, the liquid phase introduced by the eutectic reaction of the bismuth filler with the tin substrate decreased the width of the interfacial region involving abundant oxide inclusions to form a rather layer structure a few 100 nm thick consisting mainly of SnO2. It also enhanced the annihilation of the uncontacted areas at the interface. The layer of the oxide became discontinuous and coalesced with an increase in bonding temperature and pressure, and areas where no oxide inclusion could be observed at the interface were increased, when the liquid phase was formed. Owing to these effects, the bond strength rose at lower bonding temperatures and pressures when the bismuth filler was applied.
Authors: Naotsugu Yamamoto, Makoto Takahashi, Masatoshi Aritoshi, Kenji Ikeuchi
Abstract: The microstructure of the friction-bonded interface of Al alloys to low C steel has been investigated by TEM observations to reveal the controlling factor of the formation and growth of the IMC (Intermetallic Compound) layer, which caused the premature fracture at the interface even when its thickness was less than 1 μm, as reported in a previous paper. The thickness of the IMC layer observed at the interfaces of Al-Mg alloy/steel and pure-aluminum/steel joints increased almost in proportion to the friction time, but did not obey the parabolic law a characteristic kinetics of the diffusion-controlled process. Analyses of SAD patterns from the IMC layer indicate that it consisted of Fe2Al5, Fe4Al13, (Fe, Mn)Al6 and FeAl2, depending on the alloying elements. These IMCs were granular and distributed almost randomly within the IMC layer, suggesting that mechanical mixing of the steel with the Al alloy occurred at the interface. In the low C steel adjacent to the IMC layer, a zone of much finer grains than those of the base metal was observed. Its width increased with friction time and pressure, and with the growth of the IMC layer, as well. These results suggest that the superficial region of the steel underwent a heavy plastic deformation during the friction process and it had a close relation with the growth of the IMC layer.
Authors: Toshio Kuroda, Kenji Ikeuchi, Masahiro Shimada, Akihisa Inoue, Hisamichi Kimura
Abstract: Micro flash butt welding of super duplex stainless steel with Zr-based metallic glass insert was carried out using the temperature controlling system. Zr55Cu30Ni5Al10 of Zr-based metallic glass with thickness of 0.05mm and Zr metal with thickness of 0.1mm and 0.5 mm were used as the insert materials, in order to improve weldability. The specimens were mounted on the dies using a Gleeble thermal simulator, and then, flash butt welding was made. After welding, Zrbased metallic glass insert became much thinner than Zr metal insert. The super-cooled liquid in the interface protruded outside due to the superplastic deformation. The formation of the protrusion discharged the oxide films on the butting surfaces and contact surface; resulting in metallurgical bonding through the fresh surfaces. The Fe-Zr metallic compound for Zr-based metallic glass insert was hardly observed. The micro flash butt welding with metallic glass insert was successfully accomplished for super duplex stainless steel.
Authors: Toshio Kuroda, Kenji Ikeuchi, Takeshi Terajima
Abstract: Super duplex stainless steels were welded using new flash butt welding technology of temperature controlling system. The super duplex stainless steel (329J4L) and conventional duplex stainless steel (329J3L) were used. The samples were mounted in the dies using a Gleeble thermal simulator and flash but welding was made. The specimens were heated up to 1373K for 10sec, 20sec and 30sec. Flash butt welding has consisting of a two stage processes of a flash action and a contact resistance. First stage was a flash welding process and second stage was a solid state bonding process. The cross sectional microstructure of the weld bond region showed two types of a deposited fine particles region and a solid state bonding region. The grain growth was hardly observed in the weld region and the heat-affected zone. For further increasing joining efficiency of solid state bonding at the second stage, the welding time at 1373K was increased from 5 sec to 180sec. The bonding area increased with increasing welding time at 1373K and successfully welded for conventional duplex stainless steel.
Authors: Akio Nishimoto, Katsuya Akamatsu, Kenji Ikeuchi
Abstract: Pulsed electric-current sintering (PECS) was applied to the bonding of SiC (pressureless-sintered silicon carbide) to Cu (oxygen-free copper) using a mixture of Cu and Ti powders as an intermediate layer. The influences of the intermediate powders on the bond strength of the joint were investigated by observation of the microstructure. The bonding was carried out at carbon-die temperatures from 973 to 1173 K at a bonding pressure of 10 MPa for 3.6 ks. The application of intermediate layers of 100% Ti, 95% Ti + 5% Cu, and 5% Ti + 95% Cu remarkably improved the bond strength as compared with direct bonding without an intermediate powder. SEM observations of the joint with the intermediate powders revealed that a Cu solid-solution layer, a TiC layer, and a Ti5Si3 layer had covered most of the interface, similar to those observed in the friction-bonded and pulsed-electric current bonded joints of SiC to Cu in which the application of a Ti foil as an intermediate layer remarkably improved the bond strength.
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