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Volume 47, Issue 10
Displaying 1-17 of 17 articles from this issue
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Katsuhiko Ueda, Terufumi Machida2000 Volume 47 Issue 10 Pages 1051-1055
Published: October 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to achieve the higher density in a die-lubrication compacting process, an experimental investigation was conducted regarding the influence of zinc stearate lubricant added in iron powder on the green density, the friction between powder and die wall, and the friction between powders.
The lubrication of some 0.05 mass% was most suitable for the powder flowability and the axially uniform density. The die lubrication is important to reduce the die-powder friction, however, it can not improve the green density. The effect is similar as in case of graphite-added powder. The lubricant reduction is most promising when compacting pressures is higher than 700MPa in the method.View full abstractDownload PDF (355K) -
Chihiro Kawai, Yoshinobu Takeda2000 Volume 47 Issue 10 Pages 1056-1060
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn this report, the wettability of molten Al alloys with SiC powder is discussed using mercury porosimetric analysis. Al-SiC powder compacts with a composition of SiC-30mass%Al are used as the starting materials. Wettability can be evaluated from their pore size distribution after heating. In the pure Al-SiC system, the increase in temperature increases the open-pore size and the open-porosity of specimens, resulting in high wettability. The addition of a slight amount of Mg to Al significantly increases the wettability. We conclude that the decrease in surface tension of molten Al alloys is seriously effective to improve the wettability.View full abstractDownload PDF (2748K) -
Teruo Asaoka, Hiroyuki Muraoka2000 Volume 47 Issue 10 Pages 1061-1066
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe authors tried to fabricate the shape memory alloy (SMA) particle dispersed materials by pulse electric current sintering and to investigate the microstructures of particle-matrix interface. Ti-Ni alloy was used as the dispersed particles and SCM435 steel powder was selected as the matrix. In the fabricated materials, Ti-Ni particles were dispersed uniformly and almost non-deformed in their shape. The relative density was about 95%. By EPMA and by TEM observations, we confirmed the segregation of Ti and Ni at the surface of dispersed particles, and also the diffusion of Fe into the particles. As the pulse electric current sintering method has advantages of shortening the time for fabrications and lowering the temperature for fabrication, the observed interface segregation layers were more thin in compare with other fabrication method such as HIP. When the crack arrest function is expected, these interface structures are considered to be favorable, because of eliminating the transformation temperature shift in Ti-Ni particles due to local composition change.View full abstractDownload PDF (8303K) -
Yoshihisa Kishimoto, Osamu Yamashita2000 Volume 47 Issue 10 Pages 1067-1072
Published: October 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSNd-Fe-B alloy powder was granulated by a spray drying method using an organic binder in order to improve the powder flowability during feeding and compacting. In this experiment, whether or not the degree of magnetic orientation of primary particles in granulated powders is raised by applying high intensity pulsed magnetic field in compacting was studied, in order to improve magnetic properties of sintered magnets. It was found that the orientation of particles (remanences) was improved remarkably by applying high intensity pulsed magnetic field in initial process of compaction of granulated powders, so that magnetic properties of magnets are superior to those of magnets when applying only static magnetic field in compacting. The observation of granulated powders after applying magnetic field shows that granulated powders were destructed more easily by such high intensity pulsed field. The orientation of primary particles in granulated powders depends strongly on the apparent density of powders when applying pulsed field. It was very effective for improving magnetic properties of magnets using granulated powders to apply pulsed field when powders fed in die cavity are free for orientation. By means of controlling the binding strength of binder and timing of pulsed magnetic field, magnetic characteristics of magnets using granulated powders became almost equal to that of magnet using raw powder.View full abstractDownload PDF (2194K) -
Wen-bo Du, Kiyohiko Tatsuzawa, Tatsuhiko Aizawa, Junji Kihara2000 Volume 47 Issue 10 Pages 1073-1079
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe mechanical properties of the CFF-Al2O3 wire with respect to the Vickers hardness, the fracture toughness and the fracture/tensile strength have been discussed in the present investigation. Results indicate that the CFF process is valid for fabricating Al2O3 wire with enhanced mechanical properties. Residual pores in the resintered microstructure are thought to be fatal in determination of the mechanical properties, but the grain size dependence seems to be insensitive. At presence of porosity lower than 2.0%, the fracture of the CFF-Al2O3 wire is controlled by the transgranular mode, and its fracture/tensile strength achieves 1.1 GPa. However, the intergranular mode becomes dominated, resulting in a decrease in strength if porosity is higher than 2.0%.View full abstractDownload PDF (6241K) -
Bong-Gyu Park, Se-Hyun Ko, Yong-Ho Park2000 Volume 47 Issue 10 Pages 1080-1084
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn situ intermetallic matrix composites were fabricated by MA (mechanical alloying)-PDS (pulse discharge sintering) process. Matrix was Fe-28at.%Al and in situ reinforcements were TiC and TiB2. Mechanical alloying was carried out using a vibratory mill. For the Fe-AI-Ti-C alloy system, milling time was systematically changed from 1 to 400 hours to observe the effect of milling parameter. For the Fe-Al-Ti-B system, volume fraction of reinforcements was systematically changed from 0 to 25 at.%. Mechanically alloyed powders were sintered in the plasma discharge sintering system. Fe3Al matrix and in situ reinforcements, that is, TiC and TiB2 particles were successfully synthesized during MA-PDS process.View full abstractDownload PDF (3786K) -
Koichiro Morimoto, Katsuhiko Mori, Muneaki Watanabe, Eiichiro Niizuma, ...2000 Volume 47 Issue 10 Pages 1085-1090
Published: October 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAnisotropic fully dense Nd Fe-B magnets can be produced by compacting the HDDR-processed powder under an orienting magnetic field, and then by hot pressing the green compacts. In this study, we investigated orienting field dependence of the magnetic properties in the hot pressed magnets made from the Nd12.7Dy0.3Fe64.3Co16.0B6.2Zr0.1Ga0.4 powder in the different stages of the HDDR process. It was found that the semi-processed HDDR powder, in which the recombination reaction of the decomposed phases is not completed, can be more highly oriented in the applied magnetic fields less than 1190 kA/m in comparison with the fully HDDR-processed powder. The magnet with Br=1.13 T, HcJ=1280 kA/m, and (BH)mas=230 kJ/m3 can be obtained by dehydrogenating the compact of the semi-processed powder before the hot pressing.View full abstractDownload PDF (1740K) -
Koichi Kamada, Mitsuru Nakamura, Hiroshi Horie2000 Volume 47 Issue 10 Pages 1091-1096
Published: October 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe effect of boron (B) and silicon (Si) additions on the liquid-phase sintering behavior and corrosion resistance of P/M ferrite type stainless steel (SUS430L) was investigated. As a result, the addition of B improved the sintering of specimens, and the relative sintered density of 0.2mass%B and 0.2mass%B+2mass%Si added steel sintered at 1573 K were more than 97%. The high tensile strength was obtained on 0.2mass%B+2mass%Si added specimens sintered at 1473, 1523 and 1573 K, and the maximum strength was 508 MPa obtained at 1573 K. The reason was considered due to the high density of the matrix obtained by the eutectic reaction between the matrix and borides and the solid-solution hardening of matrix by Si element. On the other hand, the ductility was not improved by the addition of B and Si. This results may be due to grain coarsening and borides precipitated along the grain boundary. The specimen with 0.2mass%B and 0.2m, -ss%B+2mass%Si sintered at 1573 K were found to have an excellent corrosion resistance in a pitting corrosion test of a solution of 6 % FeCl3 (N/20 HC1). Especially, the corrosion rate of the 0.2mass%B + 2mass%Si added steel sintered at 1573 K is smaller by one sixth compared of the non-added steel. However, in the case of steels sintered at lower than 1523 K, the corrosion resistance of 0.2mass%B and 0.2mass%B+2mass%Si added steels was similar to that of the non-added steel. This tendency was probably due to a low sintered density in similar to the non-added P/M steel.View full abstractDownload PDF (5697K) -
Keizo Kobayashi, Akihiro Matsumoto, Toshiyuki Nishio, Kimihiro Ozaki, ...2000 Volume 47 Issue 10 Pages 1097-1101
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFe-48at%Cr powder was synthesized by mechanical alloying (MA) of elemental Fe (99.8mass%Fe) powder and Cr (99.9mass%Cr) powder using a planetary ball milling for 180 ks. The X-ray diffraction profile of the obtained MA powder showed Fe-Cr solid solution. The powder was consolidated using a pulsed current sintering (PCS) method at 1073 K for 0.3 ks. The structure of the consolidated bulk material was consisted of Fe-Cr solid solution with the grain size of approximately 1μm. This bulk material showed 869 MPa in tensile strength and 20% in elongation at room temperature. The mechanically alloyed Fe-48at%Cr powder was formed into the product with a complicated shape by controlling the forming condition such as an applied pressure or a cooling rate in PCS.View full abstractDownload PDF (3599K) -
Shoichi Kume, Haruo Yoshida, Kazutaka Suzuki, Naoyuki Kanetake2000 Volume 47 Issue 10 Pages 1102-1107
Published: October 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSDiamond/PSZ composites were tried to sinter by both routes of hot isostatic pressing (HIPing) under 150 MPa at 1423 K for 10.8 ks and hot pressing (HPing) under 36 MPa at 1673 K and 1773 K for 10.8 ks. The all sintering conditions are thermodynamically unstable for diamonds. When the composites were sintered by the HIPing and the HPing at 1673 K, no transformation of the diamond into graphite and no reaction products was detected in the composites by XRD analysis. In the HPing at 1773 K, also no transformation into graphite but the formation of ZrC was found in the composite. The tetragonal phase of zirconia, which is favorable to good toughness, was more remained in composites after HIPing and HPing at 1673 K than that with no diamond. The relative densities were above 97% in the composites containing diamond up to 30vol.% sintered by HIPing and in those up to 10vol.% by HPing. Dispersing diamond was effective to restrain the zirconia grain growth during the sintering in HIPing. The Vickers hardness of the composite containing 10 vol.% diamond was increased as compared with that of the zirconia with no diamond.View full abstractDownload PDF (4376K) -
[in Japanese]2000 Volume 47 Issue 10 Pages 1110
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (84K) -
Ai Yamaguchi, Shinjiro Tochihara, Takahiro Katsumata, Yoshihiro Uragam ...2000 Volume 47 Issue 10 Pages 1111-1115
Published: October 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWe measured the temperature dependence of the 2nd, 3rd and 5th higher-harmonic susceptibilities of(La1-xCax)(Ba1.75-xLa0.25+x)Cu3O7+δ, x=0.2, 0.4, 0.5, prepared by the amorphous metal-complex method. We attempted to fit the calculations based on the Kim-Anderson critical-state model to the experimental results of χn. The analysis shows that the pinning force density is enhanced with increasingχ.View full abstractDownload PDF (397K) -
Etsuro Sugimata, Syouichi Nasu, Kentaro Ohhashi2000 Volume 47 Issue 10 Pages 1116-1119
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA new compound has been synthesized in iodine intercalation of Bi2212 single crystal by using mixed powders of Fe and I2 as reactants. By this intercalation, the lattice parameter along c-axis was expanded from 15.5 (=31.0Å/2) to 18.2 Å. From an analysis of composition by fluorescent X-ray analysis microscope, it was found that only the iodine was inserted into host material. The value of lattice parameter has been shorter than one of ordinary iodine intercalation compound IBi2212 (19.05Å). The out-of-plane resistivity of new compound has remained semiconductor-like behavior after intercalation. The transition temperature (onset) TCon of this new compound was 88 K in both directions.View full abstractDownload PDF (287K) -
Masatsune Kato, Takaaki Tanaami, Yoji Koike2000 Volume 47 Issue 10 Pages 1120-1123
Published: October 15, 2000
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSA trial of the carrier doping into (Sr, Ba)2Cu3O4(Cl, Br)2 with the Cu3O4 plane, which is composed of Cu(1)O2 and extra Cu(2) sublattices, has been carried out through the partial substitution. We have succeeded in obtaining single-phase samples of Ba2Cu3-xLixO4Cl2(0≤x≤1.0). With increasing x, the α-axis tends to decrease and the c-axis is almost constant. All samples exhibit semiconductive behavior. The electrical resistivity decreases with increasing x up to 0.5 and tends to increase slightly for x>0.5 due to disorder in the Cu3O4 plane through the substitution of Li+ for Cu2+. Both of the antiferromagnetic transition temperatures with respect to Cu (1) and Cu (2) decrease with increasing x. However, the antiferromagnetic ordering in the Cu(1)O2 sublattice still remains even for x=0.5. Considering that the formal valence of Cu is + 2.2 for x=0.5, holes doped through the Li-substitution maybe localized in the Cu(2) site. We will also discuss the possibility of the appearance of the superconductivity in the present system with the Cu3O4 plane.View full abstractDownload PDF (311K) -
Ichiro Nagai, Yuji Abe, Masatune Kato, Yoji Koike, Masato Kakihana2000 Volume 47 Issue 10 Pages 1124-1127
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe prepared Li-intercalated layered niobium oxide LixACa2Nb3O10(A=K, Rb, Cs) by an electrochemical technique. The host compounds ACa2Nb3O10 were synthesized by a solid state reaction method at 850-1150°C for 10-12h. Each of the cyclic voltammograms of these compounds had one cathodic peak at--3V, indicating that the Li-intercaration occurred at this voltage. All of the intercalated compounds LixACa2Nb3O10 (A=K, Rb, Cs) showed superconductivity at 4-5K, and their x-ray diffraction pattern remained almost unchanged in spite of the Li-intercalation. For LixRbCa2Nb3O10, no superconductivity appeared up to x = 0.17, for x=0.34 and 0.46 Tc (determined as the onset of the Missner effect) was constant at 4 K, and for x = 0.62 Tc decreased slightly to 3K.View full abstractDownload PDF (244K) -
Masatsune Kato, Yuji Abe, Yoji Koike2000 Volume 47 Issue 10 Pages 1128-1132
Published: October 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe have succeeded in preparing Li-intercalated Bi-based oxychlorides with the layered structures LixBiOCl and LixBiPbO2Cl(0≤x≤1) by means of the chemical technique using a solution of n-buthyllithium in hexane and the electrochemical one. In the case of the chemical technique for both BiOCl and BiPbO2Cl, the host samples have turned black gradually and the electrical resistivity has decreased with increasing treatment-time. However, the temperature dependence of the electrical resistivity has still remained semiconductive. From the powder x-ray diffraction and ICP analyses, the products have been found to be of the single phase within the Li-content of 0≤x≤1. The time required for the Li-intercalation by the electrochemical technique has been a fraction of that by the chemical technique.View full abstractDownload PDF (351K) -
2000 Volume 47 Issue 10 Pages 1135
Published: 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (22K)
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