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Volume 49, Issue 1
Displaying 1-10 of 10 articles from this issue
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Taeko Tsubokura, Takeo Tsukada, Takeshi Nomura2002 Volume 49 Issue 1 Pages 3-8
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical property of sintered piezoelectric materials has been studied with special reference to the carbon content and sintering conditions.
It has been shown that the bending strength of PZT-based material is well explained by the residual carbon content of sintered body. Oxidizing atmosphere during firing is so effective to achieve fine and uniform microstructure and higher bending strength. Binder content of green compact also has strong effect on the bending strength. Higher content of binder has a deleterious effect on the mechanical property because it might introduce reducing atmosphere during firing.View full abstractDownload PDF (4350K) -
Ryosuke Ueyama, Nobuyuki Seki, Tamotsu Ueyama2002 Volume 49 Issue 1 Pages 9-13
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe characteristics of Cu powder used for the fabrication of termination electrodes of multilayer ceramic chip capacitors (MLCCs) was evaluated. The effects of particle diameter on the sintering characteristics of Cu powder for use as electrode films were studied. A high tapping density was obtained for all pulverized Cu powders with average particle diameter of 0.5μm, 1.0μm and 5.0μm. The experimental results revealed that pulverized Cu powders were homogeneously dispersed in the paste. From shrinkage measurements in Cu electrode films with thickness of approximately 200μm, which were formed by an applicator and sintered at temperatures from 650°C to 850°C, it was observed that films composed of 0.5μm and 1.0μm Cu powders showed a larger shrinkage than that from 5.0μm Cu powder. A similar result has been observed for the microstructure of sintered electrode films.View full abstractDownload PDF (3184K) -
Chio Ishihara, Kazuo Asaka, Ryoichi Urao2002 Volume 49 Issue 1 Pages 14-18
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThrough previous studies of materials for iron powders insulated with the resin, we have developed anode reactor powder cores which are used to protect Thyristor Valves for HVDC (High-Voltage Direct Current) transmission systems. However, their core losses are not necessarily low. Then, further studies on insulating methods of iron powders and annealing conditions of the powder cores were carried out to decrease the core losses.
As the results, we have developed much superior powder cores which show higher specific resistivity than 5 S2m by researching suitable interfacial activators and rust preventive in the insulation materials. Further, by studying on annealing conditions of these new powder cores, we have been able to decrease the core losses. Although the specific resistivity decrease with the annealing process, it can be maintained more than 0.01Ωm which is considered to be minimum value to maintain their core losses at low level, as the newly developed powder cores show higher specific resistivity than 5Ωm before annealing.View full abstractDownload PDF (394K) -
Ken Kikuchi, Makoto Sugamata, Junichi Kaneko2002 Volume 49 Issue 1 Pages 19-24
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWith a purpose of attesting strength increases by internal oxidation of aluminum alloys, P/M materials of Al-8mass%Fe alloy was prepared by mechanical alloying from three different starting materials. That is, Fe was added to aluminum as elemental Fe, as Al3Fe intermetallic compound and as Fe2O3 oxide. Mechanically alloyed powders were consolidated by hot-extrusion to the P/M materials of which constituent phases, microstructures and mechanical properties were examined. In case of Fe2O3 addition, Al-Fe alloy was obtained by reduction of Fe2O3 accompanied with formation of Al2O3. The P/M materials with addition of Fe2O3 showed the highest tensile strength of 555 MPa at room temperature, and 340 MPa at 573 K. Hence, strength was increased by internal oxidation of aluminum alloys.View full abstractDownload PDF (2130K) -
Toshikazu Sugimura, Yoshiyuki Tanaka2002 Volume 49 Issue 1 Pages 25-31
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAn electron emitter pellet for low temperature operating cathode has been developed by integrating a mixture of (Ba, Sr, Ca)CO3 powder, Ni powder and Sc2O3 powder using hot isostatic pressing (HIP). During the exhaustion process of cathode ray tube (CRT), an emitting layer composed of oxide emitter is formed on the pellet surface. During emission, this emitting layer plays an important role. In this study, we performed life tests of the pellet at high current density. Emission properties were evaluated by measuring maximum cathode currents and observing cathode images. In addition, time course changes of the emitting layer were examined. Superior life characteristics of less than 3% and 20% reduction in the maximum cathode current 1.5×104h and 3.5×104h, respectively, after the start of the high current application life test with an average current density of 3A/cm2, ten times as large as practical current density of CRTs, were obtained. These conditions reveal that the pellet exhibits superior life properties against high current loads. The emitting layer on the pellet surface develops irregularities 1.5×104h after the start of the life test, with a part of Ni exposed. The emission properties of the pellet do not deteriorate regardless of such irregularities in the emitting layer; this is considered to be because Ba is supplied from the inside of the pellet, and BaO covers the entire pellet surface.View full abstractDownload PDF (4743K) -
Tetsuji Hoshika, Yutaka Hiraoka, Masahiro Nagae, Jun Takada2002 Volume 49 Issue 1 Pages 32-36
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCarbon addition by solid carburizing was performed for Mo and Mo-Ti alloys. The Vickers hardness tests was performed for these samples. The Vickers hardness tests estimated the hardness of a sample. The hardness distribution was investigated from the sample surface to the piece thickness direction of a sample. Existence, size and identification of precipitate was examined by TEM and EDX.
The hardness of Mo added carbon was of the same grade compared with that of the recrystallized ones. The hardness of Mo-Ti added carbon alloys was higher than that of the recrystallized ones. The precipitate has not been checked in Mo. However the precipitate was able to be checked in Mo-Ti alloys. The precipitate was TiC. The increase in a hardness of Mo-Ti alloys added carbon was due to precipitation hardening. In the case of Mo-Ti alloys, there is possibility of internal carburizing.View full abstractDownload PDF (6725K) -
Hideo Yoshinaga, Akio Kawabata, Yongyao Xia, Tetsuo Sakai2002 Volume 49 Issue 1 Pages 37-43
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe have prepared V-Sn alloys by powder metallurgy process as a new negative electrode material for Lithium ion battery. The cycle life was significantly improved by formation of intermetallic compound V2Sn3. The V2Sn3 alloy showed a rechargeable capacity of ca.500mAh/g over 50 cycles in the charge/discharge range of 0-1.5V.View full abstractDownload PDF (1740K) -
[in Japanese]2002 Volume 49 Issue 1 Pages 46
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (88K) -
Hirotsugu Takizawa, Takahiro Yamashita, Takeshi Sasaki, Kyota Uheda, T ...2002 Volume 49 Issue 1 Pages 47-51
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA new intermetallic compound, Mn3Ge, has been synthesized from the elemental components under high-pressure condition. The Rietveld analysis of the powder X-ray diffraction data revealed that the compound crystallizes into the cubic L12-type (Cu3Au-type) structure with the lattice parameter of a=0.38019 (3)nm. The result, as well as our former results on high-pressure synthesis of manganese germanides, suggests a remarkable change in binary Mn-Ge phase diagram under high-pressure condition. Mn3Ge exhibits metallic conduction and ferromagnetic behavior with a Curie temperature of 400K. The saturation magnetic moment is 0.87μB/Mn, indicating a possible itinerant electron ferromagnetism. The magnetic properties of Mn3Ge are discussed with isomorphous compounds and structurally related perovskite-type Mn3MC (M=A1, Ga, In, Zn, Sn) compounds.View full abstractDownload PDF (348K) -
Eiji Yuasa, Kosuke Yamaguchi, Katsuyoshi Kondou, Tatsuhiko Aizawa2002 Volume 49 Issue 1 Pages 52-57
Published: January 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHot working of intermetallic compound is difficult because of its high mechanical strength at high temperature, but it seems to be possible by the forming under condition of solid-liquid state that is formed by heating at fusion temperature of lower melting metal in powder mixture. This study was done on synthesis of intermetallic compound from the solid-liquid state when Al-(40-44)mass%Ni powder mixture was heated with various heating rates. The AI-Ni solid solution forms at lower temperature than the melting point of aluminum and then the solid-liquid state forms with high exothermic heat by fusion of the solid solution. After solidification from this state, microstructures of the Al-Ni alloy are constituted with Al3Ni2 and A13Ni intermetallic phases and eutectic structure. The same microstructure in the Al-Ni alloy backward-extruded under condition of the solid-liquid state is constituted as the isochronally heated powder mixture.View full abstractDownload PDF (3430K)
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