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Volume 43, Issue 9
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[in Japanese]1996 Volume 43 Issue 9 Pages 1064
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (72K) -
Yoshiyuki Nasuno, Minoru Osada, Masato Kakihana, Hiroshi Yasuoka, Shin ...1996 Volume 43 Issue 9 Pages 1065-1069
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTwo types of Ca-substituted Y123 phase, (A) Y1-0.75xBa2-0.25xCaxCu3O7-d and (B) Y1-xCaxBa2Cu3O7-d have been prepared by a polymerized complex method X-ray powder diffraction and complex magnetic susceptibility measurements have shown that only type (A) is virtually of single phase without any impurities such as BaCuO2 and Y2BaCuO5. The superconducting transition temperature Tc decreases from 92.2K (x=0) to 83.2K (x=0.2) with increasing x in (A). Furthermore, we investigated the effect of Ca-substitution on phonon Raman spectra of type (A) by using a micro-Raman spectrometer. Ba and 0(4) phonons are significantly shifted towards lower frequencies by 3cm-1 and 4cm-1, respectively, when x is increased from 0 to 0.2. A possible origin of the decrease in both Tc and Ba-0(4) layers phonon energies are discussed in terms of both hole doping in the CuO2 planes and internal pressure induced by the Ca-substitution.View full abstractDownload PDF (291K) -
Shinjirou Tochihara, Hiroshi Yasuoka, Hiromasa Mazaki, Motoharu Komats ...1996 Volume 43 Issue 9 Pages 1070-1075
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFor the study of magnetic properties of high-Tc superconductors, we measured harmonic ac susceptibilities Xn=Xn-iXn " of a single-crystal YBa2Cu3O7-d thin film immersed in an external field H(t)-Hde+Hey cos(ωt), where Mc (≥0) is a do bias field and Hac (> 0) is an ac field amplitude. Measurements of Xn were carried out for n=1, 2, 3, 5, 7 and μ0Hac=0.1mT. The fundamental frequency was 132Hz. The observed results were analyzed within the construct of the Kim-Anderson model for critical-current density and the modified Bean model which takes into consideration the surface barrier and the lower critical field. The characteristics of the experimental results were well reproduced by the modified Bean model, suggesting that the surface barrier plays an essential role for the thin film.View full abstractDownload PDF (293K) -
Toshio Egi, Jian-Guo Wen, Kiyoshi Kuroda, Hiromi Unoki, Naoki Koshizuk ...1996 Volume 43 Issue 9 Pages 1076-1080
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe have studied the superconducting properties of Nd(Ba1-xNdx)2Cu3O7-δ (Nd123, x≈0.1) single crystals grown by the traveling-solvent floating-zone method under 0.1% O2 in Ar atmosphere. An anomalous peak effect in the magnetization hysteresis (M-B) loop is observed in the Nd123 single crystals as well as in the Nd 123 bulk crystals prepared by the oxygen-controlledmelt-growth (OCMG) method. The critical current density (Jc) of the Nd123 single crystals is 70, 600 A/cm2 in 1.0T at 77K for the applied field perpendicular to the ab-plane. The existence of Nd and Ba composition variation in the matrix of Nd123 crystals is observed by an analytical TEM equipped with a cold field-emission gun. The high Jc value of the Nd123 single crystals in the applied field is explained by the field-induced pinning centers caused by the Nd-Ba substitutions in the Nd123 matrix.View full abstractDownload PDF (5879K) -
Kunio Matsuzaki, Koichi Shimizu, Akihisa Inoue, Tsuyoshi Masumoto1996 Volume 43 Issue 9 Pages 1081-1086
Published: September 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAg/Bi2223 multilayered wires and tapes were prepared by the jelly roll method. The wires are composed of 2223 and Ag layers and exhibit supercondcutivitiy at temperatures above 77 K. The critical current density (Jc) of 3200A/cm2 was obtained for the wire of 2 mm in diameter. The multilayered tapes consist of a highly oriented 2223 phase over the whole tape region. Jc of the multilayered tape increases with decreasing tape thickness and reaches a maximum value of 8200 A/cm2 at 0. 25 mm in thickness. The Jc is further enhanced by the thermomechanical treatment and the high Jc of 17200 A/cm2, corresponding to Ic of 29. 2 A is attained. Moreover, the multilayered tape of 0. 25 mm in thickness is bent up to a bending strain of 0.6% without detriation of Jc. These results indicate that the multilayering with Ag is effective to improve Jc of the Bi2223 superconducting oxide wire.View full abstractDownload PDF (1941K) -
Yuji Zenitani, Shuji Sahoda, Jun Akimitsu, Nobuhiko Kubota, Muneo Ayab ...1996 Volume 43 Issue 9 Pages 1087-1089
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe report a new superconductor, (Ca, A)2CuO2+yBr2-y:A=(Na, K)(Tc=24 K) with apical bromines synthesized under high pressure. X-ray powder diffraction shows that the superconducting phase has a tetragonal structure with a=3.858 Å, c=17.257 Å. This structure is so called La2CuO4 (214) type with an apical site of octahedral CuO6 being almost occupied by the bromine atoms.View full abstractDownload PDF (205K) -
Takashi Kiyama, Kazuyoshi Yoshimura, Koji Kosuge, Yasunori Ikeda, Yosh ...1996 Volume 43 Issue 9 Pages 1090-1094
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe report here the results of Debye-Scherrer X-ray diffraction measurements in the temperature range from 12K to 300K of the perovskite compounds SrRuO3 and CaRuO3. We show that SrRuO3 indicates an clear anomaly with the temperature dependence of the unit-cell parameters and volume below its ferromagnetic transition temperature Tc of 160K through magnetovolume effect. In particular, the volume of SrRuO3 is almost constant below Tc, and invar effect is discovered for the first time in transition-metal oxide, which is seen in 3d transition-metal itinerant magnets, e.g., Fe-Ni alloy. Therefore, it is concluded that SrRuO3 is classified to a moderately weak itinerant ferromagnet. On the other hand, CaRuO3 shows no anomaly in the variation of the volume with temperature, suggesting that magnetic ordering does not occur in this compound.View full abstractDownload PDF (299K) -
Yasuo Takeda, Chikara Okazoe, Nobuyuki Imanishi, Osamu Yamamoto, Mikio ...1996 Volume 43 Issue 9 Pages 1095-1098
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCa1-xSrxFeO3-z and SrFe1-xCoxO3-z (0≤x≤1, z-0.1) of the cubic perovskite type were prepared by treating grossly oxygen-deficient samples at room temperature using an electrochemical oxidation technique. In the case of SrFe1-xCoxO3-z, the ferromagnetic curie temperature has been found to be raised above 3 00K for 0.4≤x≤1.0 (340K at x=0.4) by the electrochemical oxidation method. Only a few hundred mV of electrode potential has relatively more oxidation power than a considerable high oxygen pressure, however, the lack of stability (drcrease of oxygen content) after electrolysis is a weak-point.View full abstractDownload PDF (247K) -
Katsuhiko Shiomi, Sukeo Fujita, Yukitoshi Inoue1996 Volume 43 Issue 9 Pages 1101-1105
Published: September 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWith regard to the CRT display, the deflection yoke is required to achieve higher picture quality. To achieve it, we currently use the ferrite core of which inner surface was ground. The picture quality is closely related to the inside diameter of the ferrite core. Therefore, we made a study on the heat shrinkage of the ferrite core to be used for the saddle-saddle type deflection yoke. We are reporting here the method of reducing the shrinkage of the ferrite core to improve the accuracy of its inside diameter. With a view to achieving higher bulk density (BD), we selected optimum iron oxide out of main materials in various conditions and improved both the uniformity of the diffusion of polyvinyl alcohol (PVA) and the particle size distribution. As a result, we could reduce the shrinkage of the ferrite core from 14.5% to 10.0%. By this method, we could achieve the same performance of the deflection yoke as in the case of the ferrite core of which inner surface was ground.View full abstractDownload PDF (3509K) -
Shigeru Unami, Osamu Furukimi, Satoshi Uenosono, Kuniaki Ogura1996 Volume 43 Issue 9 Pages 1106-1110
Published: September 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSA prealloyed lCr-0.3Mo-0.3V(mass%) steel powder was developed to obtain the high strength sintered compacts. This new sintered 1Cr-0.3Mo-03V powder compact, which is Mn-less, made it possible to extend the range of the cooling rate after sintering to attain higher strength than that of sintered 1Cr-0.3Mo steel, and gave a tensile strength of more than 800 MPa and a rotating bending fatigue strength of 31OMPa at the cooling rates of 1 to 30°C/min. The wide range of cooling rates at which high strength can be obtained was attributed to a decrease in hardenability and the production of a fine pearlite structure by V addition. The improvement of the strength for the compacts added V is attributed to the precipitation hardening of V carbonitrides, as well as a narrow pearlite lamellar spacing.View full abstractDownload PDF (2522K) -
Mitsuru Nakamura, Koichi Kamada, Sadato Hiratsuka, Yuji Nomura1996 Volume 43 Issue 9 Pages 1111-1116
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe addition of silicon (Si) and boron (B) to SUS304L stailess steel powders has been examined, aiming at lowering the liquid-phase sintering temperature, and at improving the mechanical properties and corrosion resistance. Addition of Si resulted in the duplex structures of austenite (γ) and ferrite (α), which gained the strength due to the crystallization of α phase. By the over addition of Si, the ductility was lowerd. Addition of B improved the ductility, which was due to the precipitation of fine borides around the grain boundaries. These precipitation formed the spherical pore. By the simultaneous addition of both elements, the sintering temperature was lowerd to 1500K, which was lower than that of single element addition by 100-150K. The specimens showed an improved mechanical properties such as 595MPa in tensile strength and 36.7% in elongation. The corrosion resistance by intergranular corrosion test of a boiling solution of 65% HNO a was not improved by the addition of Si and B. This may be due to low sintering density and the existance of many pore defect.View full abstractDownload PDF (2610K) -
Tatsuya Shiogai, Norikazu Sashida, Keizou Tsukamoto, Chitake Yamagishi1996 Volume 43 Issue 9 Pages 1117-1121
Published: September 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe macroscopic inhomogeneity of Sialon ceramics was studied. There were two regions in the sintered body. One of regions was green region and the other was brown region. The fracture toughness of the sintered body with two regions had large difference, and the green region had low toughness. The regions were analyzed by UV spectroscopy, EPMA, XRD, SEM, and TEM. There was no difference in microstructure, but there was difference in electronic state, chemical composition, and crystal phase. From these fact, it is considered that the origin of macroscopic inhomogeneity is due to gas generated from decomposition of Sialon. The gas is shut in sintered body when densification is fast at surface, and the chemical composition of grain boundary or grain is changed by reaction with gas.View full abstractDownload PDF (1319K) -
Takashi Hosokoshi, Shigeru Ito, Kazuo Akashi1996 Volume 43 Issue 9 Pages 1122-1126
Published: September 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to obtain sintered FeSi2, the mixed powder of Fe and Si has been hipped at below the decomposition temperature of 986°C. In this process, the reaction and the densification have been proceeded simultaneously. Before the hipping of powders, the reaction of Fe plate and Si plate was examined to understand the reaction of Fe and Si under hipping condition. It was found that high temperature and low pressure accelerated the reaction. Based on the results, hipping conditions of the powder were decided. Single phase of FeSi2 was obtained under the hipping condition of 850 - 900°C, 50MPa and 30min -4hours. However, the relative densities of the hipped specimens were 82 - 90%. To obtain higher density, the mixed powder was hipped under 50 MPa to be caused the reaction completely, and then was densified under high pressure of 200MPa. Applying this 2 stage hipping, the relative density increased up to 98%. It is concluded that HIP technique is useful for the materials which transform at high temperature.View full abstractDownload PDF (4921K) -
Takahiro Yamakawa, Masako Kataoka, Tohru Ezaki, Shigeru Takahashi, Yos ...1996 Volume 43 Issue 9 Pages 1127-1131
Published: September 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIt has been reported by our previous paper on the sintering behavior of lead zirconate titanates (PZT) that additive MnO promotes the grain growth and suppresses the densification of PZT. This paper reports the sintering behavior of PZT with various amount of additive MnO and Sb2O3. Additive MnO promotes the grain growth of PZT, while additive Sb2O3, supresses the grain growth even with additive MnO together. It was found, however, that Sb2O3 acts as a sintering aid in the case of sintering PZT with 0.5 mass% Sb2O3 at 1100°C: this condition attains the maximum density of all the specimen. It also revealed that the grain boundary diffusion is dominant in PZT with no additive or with only MnO, and that volume diffusion is dominant in PZT with only Sb2O3 or the both of Sb2O3 and MnO.View full abstractDownload PDF (1409K) -
Takahiro Yamakawa, Masako Kataoka, Tohru Ezaki, Shigeru Takahashi, Yos ...1996 Volume 43 Issue 9 Pages 1132-1135
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe mechanism of shrinkage during sintering was investigated on PZT ceramics. Nb2O5 and MnO was added to PZT calcined powder. The mechanism of shrinkage was determined from the shrinkage-time curves. The mechanism of shrinkage and grain growth changed depending on the Nb2O5/MnO ratio. The dominant mechanism was volume diffusion when the Nb2O5/MnO ratio was larger than 6. On the other hand, the volume diffusion was inhibited when the Nb2O5/MnO ratio was less than 4. The grain growth was inhibited in the former conditions, while it was promoted in the latter conditions.View full abstractDownload PDF (2104K) -
Takahiro Yamakawa, Masako Kataoka, Tohru Ezaki, Shigeru Takahashi, Yos ...1996 Volume 43 Issue 9 Pages 1136-1140
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of Ag and PbO on the sintering behavior and the piezoelectric properties of PbSr(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 system has been studied. A small addition of Ag enhances the value of εr. and Kr. In the specimen with Ag addition, the grain growth was observed by use of SEM. The shrinkage vs temperature curves showed that the shrinkage of the specimen with Ag addition abruptly increases from 900°C and the value of shrinkage at 1100°C is as twice as the additive-free specimen. The shrinkage vs time plots revealed that the grain boundary diffusion is dominant on the sintering of PMN-PZT with Ag and Pb addition.View full abstractDownload PDF (2213K) -
Akihiro Matsumoto, Kunisuke Andoh, Kiyotaka Katoh1996 Volume 43 Issue 9 Pages 1141-1146
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSRuAl is one of the potentially useful intermetallics with a high melting temperature(2333K) as a structural material. Ru100-xAlx(x=45, 47.5, 50, 52.5, 55at%) powders were prepared by mechanical alloying (MA). The MA powders were subsequently consolidated by Plasma Activated Sintering process(PAS) at 1673-1773K for 10 minutes under 50MPa pressure. Each compact had sub-micron structure, which were consist of Ru and RuAl for 45, 47.5 and 50 at%Al compacts, RuAl and RuAl2 for 52.5 and 55 at%Al compacts. Compressive tests were carried out for Ru-Al compacts at room temperature. Some of them below 50 at%Al exhibited compressive yield stress of 2.0-2.8 GPa and compressive yield strain of more than 25%.View full abstractDownload PDF (5552K) -
Tatsuro Isomoto, Hiroshi Nagai1996 Volume 43 Issue 9 Pages 1147-1152
Published: September 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPowder metallurgy (PM) SUS304 stainless steels consolidated by hot extrusion process with different oxide inclusions are investigated in terms of tensile properties and creep rupture properties at elevated temperatures. Formation of oxides at powder surfaces and within powders is dependent on the chemical composition: An addition of Al, Mn and Si generated Al, Cr-Mn and Si oxides, respectively, while Cr oxides form without additions of those elements. The ductility of PM material is reduced by Al oxides in the high temperature tensile tests above 800°C even though the material with Al oxides has a low level of oxygen content. Furthermore, Al and Si oxides in the PM materials are more detrimental to creep rupture strength at 950°C than Cr or Cr-Mn oxides.View full abstractDownload PDF (4484K)
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