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Volume 49, Issue 3
Displaying 1-13 of 13 articles from this issue
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Tadashi Igarashi2002 Volume 49 Issue 3 Pages 163-171
Published: March 15, 2002
Released on J-STAGE: November 19, 2010
JOURNAL OPEN ACCESSMany strengthening and toughening mechanisms have been introduced into molybdenum alloys to overcome brittleness at low and high temperature. From the onset of development of molybdenum alloys, carbide particles have played important roles in the improvement of strength and toughness of molybdenum. Recently, strengthened and toughened sintered-molybdenum-alloys with fine grains and dispersed carbide particles have been developed. Carbide particles in the alloys not only inhibited grain growth at 2470K(0.85 Tm, Tm: melting point/K) and strengthened to 1470K(0.5Tm) through the fine grain structure but also improved brittleness of grain boundary to 180K(0.06Tm). Moreover, superplasticity with elongation of 550% was observed at 1770K(0.6Tm).
The progress of molybdenum alloys strengthened by carbides, the behavior of carbides in molybdenum alloys at high temperature, and the development of high performance sintered-molybdenum-alloys with fine grains and carbide particles were described in this paper.View full abstractDownload PDF (2615K) -
Norimasa Tsunekage, Harushige Tsubakino2002 Volume 49 Issue 3 Pages 172-177
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFor the purpose of improving the impact properties of ferrite-pearlitic microalloyed steels through the refinement of structure, the steels with finely dispersed sulfides were produced by P/M process. In these steels, average manganese sulfide size was one-tenth of that in conventional steels (I/M steels) and the number of inclusions was increased about two digits. The ferrite-pearlite grain size was decreased by these inclusions. Although the impact values of the steels were increased by refinement of ferrite-pearlitic structure, they were decreased by the increase of the number of inclusions. Consequently, the impact value of the steels were not improved in comparison with conventional steels.
Therefore, it is necessary to decrease the number of sulfides by controlling the sulfides slightly larger than those in the P/M steels. In this case, it is expected that the ferrite-pearlite grain size will become finer by the increase of intragranular ferrite in spite of increasing the prior austenite grain size.View full abstractDownload PDF (5385K) -
Kunio Matsuzaki, Masaharu Takahashi, Toshio Sano2002 Volume 49 Issue 3 Pages 178-182
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAZ91 alloy powders produced by gas atomization were consolidated by hot-rolling. The obtained AZ91 alloys have a density more than 98% of that of the ingot alloy when rolled to 70% reduction and at a temperature above 623K. The decrease of rolling temperature from 723 to 523K increases a hardness from 95 to 110HV, and reduces a friction coefficient and wear depth, resulting in the improvement of wear properties. The tensile strength of 330 MPa is obtained for the sample rolled at a temperature above 623 K. On the other hand, the consolidation at a temperature below 623 K causes the generation of cracks during hot-rolling and decrease a tensile strength. It is expected that an optimization of rolling condition at temperatures below 623 K would inhibit the generation of cracks, leading to the improvement of tensile strength.View full abstractDownload PDF (2848K) -
Yasuki Miyakoshi, Kohji Takazawa, Kohsuke Tagashira, Shuichi Kamota, H ...2002 Volume 49 Issue 3 Pages 183-188
Published: March 15, 2002
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe effect of carbon addition on microstructure and mechanical properties of WC-37mass%Fe sintered alloys has been investigated. These alloys are expected to be used instead of WC-Co alloys as stress relief layer materials for the sinter-bonding method of cemented carbide and carbon steel. The amounts of mixed carbon powder in binder material (iron and carbon powder) of the WC-37mass%Fe alloy green compacts are 0, 0.77, 1.25 and 2.00 mass%. These compacts were sintered at various temperatures in the range from 1463 to 1583 K. The 0, 0.77, 1.25 and 2.00mass%C added alloy compacts showed complete densification at 1553, 1543, 1533 and 1513 K, respectively. These sintered alloys are basically composed of tungsten carbide grains and binder metal, and fine pearlite structure is observed in binder metal parts for all alloys except 2.00mass%C added alloy. In addition, (Fe, W)6C, that is, η phase particles of 10-100μm in diameter were formed in 0 and 0.77mass%C added alloys, and needle-like cementites of 100μm in length were formed in 2.00mass%C added alloy. The hardness was 74-76HRA independently of carbon content, but the maximum bending strength of 2.31 GPa was obtained for 1.25mass%C added alloy. The fracture of the other alloys may be caused by the existence of coarse η phase particles or needle-like cementite.View full abstractDownload PDF (1943K) -
[in Japanese]2002 Volume 49 Issue 3 Pages 190
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (85K) -
Yuichi Shimakawa, Yoshimi Kubo2002 Volume 49 Issue 3 Pages 191-197
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCrystal structures and ferroelectric properties of SrBi2Ta2O9, which is used for FeRAM, are reported. Structure analysis using neutron diffraction data reveals significant distortion of the structure. The pronounced structural distortion of the perovskite-type unit leads to larger ferroelectric polarization and higher Curie temperature. Crystal structures and ferroelectric properties of an A-site substitution system, (Ca, Sr, Ba)Bi2Ta2O9, and a B-site substitution system, SrBi2(Ta, Nb)2O9, are also reported. Degradation of SrBi2Ta2O9 under reducing conditions is investigated and the degradation mechanism is discussed from a structural point of view.View full abstractDownload PDF (495K) -
Toshihiko Tani, Eiichiro Fukuchi, Toshio Kimura2002 Volume 49 Issue 3 Pages 198-202
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe effects of pre-sintering conditions were investigated on the final density and texture of piezoelectric Bi0.5(Na, K)0.5TiO3 (BNKT) ceramics prepared by the reactive templated grain growth (RTGG) method. Bi4Ti3O12 (BiT) platelets were used as a reactive template for the fabrication of BNKT with a preferred <100> orientation. The application of cold isostatic pressing (CIP) after the in-situ formation of regular perovskite-type BNKT was effective to increase green density before sintering and thus to increase the final density. The CIP treatment after the completion of in-situ conversion from layered perovskite into regular perovskite, however, resulted in sintered ceramics with the lower degree of orientation. The CIP treatment after the partial in-situ formation of perovskite phase produced both dense and highly textured BNKT ceramics.View full abstractDownload PDF (1691K) -
Masayuki Fujimoto2002 Volume 49 Issue 3 Pages 203-210
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSHigh-speed laser drilling using low laser power and flexible circuit layout were applied to the fabrication of 3-dimensional circuits in multilayer ceramics of miniaturized chip inductors and high-frequency power amplifier modules. The optimized combination of pulse YAG laser energy and the laser absorption coefficient of machined materials realized ultra-fine through-holes formed in thin ceramic green sheets without damaging plastic film where ceramic slurry was cast. Laser drilling based on thermal ablation.View full abstractDownload PDF (4572K) -
Yasuhiro Sasaki, Mitsuru Yamamoto, Takeshi Inoue2002 Volume 49 Issue 3 Pages 211-217
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSLow-profile inverter power sources are increasingly required for backlight systems of liquid crystal display. A great deal of attention has been focused on the application of miniaturized transformers to such power sources. The output performance of piezoelectric transformers, which operate in the third order longitudinal vibration mode with dimensions of l 42 mm×w 5.5 mm×t 1.4 mm, was studied. The piezoelectric ceramic material: 0.05Pb(Mn1/3Sb2/3)O3-0.48PbZrO3-0.47PbTiO3 was employed for these transformers. The values of efficiency for the transformers reach maximum when connecting a load resistance of around 100 kΩ which is assumed to be that of a cold cathode fluorescent lamp. The transformer with seven ceramic layers in the driver section, generates an output power of 3 W and shows the step-up voltage ratio over 60.View full abstractDownload PDF (3005K) -
Hiroshi Osada, Hirokazu Hirayama, Shigeki Chiba, Kyoshiro Seki2002 Volume 49 Issue 3 Pages 218-222
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAt present the artificial lipid films, ZnO, SiO2 and etc. have been utilized for the electrical measurements on taste or odor of various foods. The electrical property of a MnxZn1-xFe2O4 composite metal oxide thin film (CMF) changes depending on a sort of a molecule and an ion absorbed physically on its surface, so it could be applied to the taste sensor. We investigated application to the drink recognition sensor of the CMF and constructed Drinking water Recognition System (DRS). The films with 1.5 μm-thickness is prepared on Al2O3 substrate by the sputtering method and the subsequent annealing process. The multi channel recognition system combined with the plural sensors having different electrical properties by the preparation conditions can be clearly distinguished the kinds of drinking waters from output patterns. In this paper, the construction of the DRS and the recognition results for various drinking waters by DRS are discussed.View full abstractDownload PDF (2010K) -
Hideyuki Okinaka2002 Volume 49 Issue 3 Pages 223-227
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCeramic electronic components have generally been manufactured by the static firing of green bodies in a sagger. In this paper, we studied a dynamic rotary firing method in which the sagger is rotated during the firing process. It prevented shape defect such as bending and sticking between samples, and reduced the distribution of the electric characteristics. It was found that the optimized sample locations in a sagger and conditions of rotations prevented appearance defect and reduced the distribution of dimensions even when green bodies were put at random locations. It was proved that the introduction of the rotary firing process could improve the productivity and reduce the energy consumption and especially the manufacturing cost drastically when the manufacturing scale is appropriate for it.View full abstractDownload PDF (3341K) -
Keijirou Terashita, Keisuke Imamura2002 Volume 49 Issue 3 Pages 228-236
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis study was conducted to realize densely packed negative electrode plates for lithium ion secondary batteries through kneading and dispersion process. Several kinds of pastes with different viscosity were made by controlling the amount or concentration of thickener added to them and the relationship was examined between the viscosity of those pastes and the films made from them. Graphite was chosen as the negative electrode material. Films were made from each pastes containing graphite particles of certain diameter or mixture of graphite particles of different diameters. Then it was studied how the distribution of particle diameter affected on the film density. As a result, it was found that the mixture of graphite particles of different diameters could make densely packed film. It was confirmed from SEM photographs that the surface and the cross section of the film were both densely packed. Besides, it was also found that there was not a clear relationship between the tapping density of the powder mixture and the film density.View full abstractDownload PDF (3055K) -
Masahiko Mizukami, Hiroshi Yoshida, Akira Ichida2002 Volume 49 Issue 3 Pages 237-241
Published: March 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMicro-ball bump technology has been developed for high density flip chip (FC) interconnection of high Performance LSI chips. Thick solder plated balls with copper core of 40-100μm diameter were prepared and tested. This micro-ball is valuable for inner-bump of high density stacked package.View full abstractDownload PDF (3516K)
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