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Volume 46, Issue 7
Displaying 1-16 of 16 articles from this issue
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Ryoji Kanno1999 Volume 46 Issue 7 Pages 689-695
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSLayered rocksalt oxides containing lithium are promising cathode materials of secondary lithium battery. Their physical properties, however, vary significantly depending on the synthesis conditions and materials design based on their structure-property relationships is important for future materials developments. The relationships between the structures, phase relationships, and physical properties were studied in order to improve their cathodic properties. The compositions and structures were determined for lithium nickel oxides using X-ray and neutron Rietveld analysis and its magnetic properties were also studied. New cathode candidates based on iron oxides were synthesized by soft chemistry method and its structures and cathodic properties were studied.View full abstractDownload PDF (623K) -
Pascal Mosbah, Susumu Shima, Anne-Marie Habraken, Robert Charlier1999 Volume 46 Issue 7 Pages 696-704
Published: July 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSFrom experimental data for an iron powder and constitutive equations based on the modified Cam-Clay model, simulation of an axi-symmetric multi-stepped part has been achieved. In the first part of this paper, details of the constitutive relation are discussed. In the second part, the simulation of a compaction process for a multi-stepped part has been carried out. The phenomena arising along the compaction are thereby discussed: the piece rise from the lower punch during the compression and defects in the piece at the end of the compression. In the third part of this paper, results of numerical simulation are compared with experiments and it is shown that the forces exerted on the tools are in the same range of the experimental ones.View full abstractDownload PDF (863K) -
Makoto Kobayashi, Yutaka Hiraoka, Masahiro Nagae, Jun Takada1999 Volume 46 Issue 7 Pages 705-709
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn order to investigate the effect of dispersion of fine nitride particles on the low-temperature toughness of molybdenum, bend tests were performed for TZM alloy which had been internally nitrided by N2 gas and demonstrated surface hardness of 250Hv and 300Hv. In this study the low-temperature fracture strength and ductility were represented by critical stress and critical temperature, respectively.
The results are summarized as follows. (1) Yield strength of the nitrided specimens was generally much higher than that of the recrystallized ones. (2) Critical stress of the nitrided specimens was approximately as high as that of the recrystallized ones. (3) Fracture mode of the nitrided specimens was almost similar to that of the recrystallized ones. Transgranular fracture was predominant. (4) Ductility of the nitrided specimens was much lower than that of the recrystallized ones. These results are attributed to the distribution of nitride particles. Very fine nitride particles were observed predominantly in the matrix, but not at and near the grain boundaries.View full abstractDownload PDF (1876K) -
Kiyokata Iizumi, Nobukazu Yoshikawa, Katsuya Kudaka, Shigeru Okada1999 Volume 46 Issue 7 Pages 710-714
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCr2B, CrB and CrB2 ceramics were prepared by hot-pressing of the powders synthesized via the solid state reactions between metallic chromium and amorphous boron powders. Cr2B ceramics were prepared in the temperature range of 1200-1600°C. CrB ceramics were prepared in the temperature range of 1500-1900°C. CrB2 ceramics were prepared in the temperature range of 1400-1900°C. It was observed that CrB2 possesses more excellent sinterability than Cr2B amd CrB. The hardness of CrB2 ceramics increased with the sintering temperature up to 1700°C and then decreased owing to grain coarsening. As an excellent etching method of CrB2 ceramics, the electrolytic etching method was developed.View full abstractDownload PDF (3256K) -
Katsuyoshi Kondoh, Manabu Hashikura, Yoshinobu Takeda1999 Volume 46 Issue 7 Pages 715-721
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSEffects of the Si content and Si crystalline size on damping property of Powder Forged (P/F) Al-Si alloys were investigated by a Fast Fourier Transformation (FFT) analyzer. A quantitative image analysis method was successfully used to determine a mean diameter and distribution of Si crystals in the aluminum alloy. The damping capacity δ strongly depends on the mean diameter of Si crystals. δ of heat treated specimens with Si crystals of 2 to 5 micron meters is 4 to 25 times smaller than that of as-forged specimens with those of 1 to 5 micron meters. It indicates that the vibration occurred by knocking on the specimen is absorbed at boundary between Si particles and aluminum matrix. Therefore, fine distribution of Si crystals and/or elimination of crystal coarsening contribute to the good damping property.View full abstractDownload PDF (4579K) -
Kazuo Asaka1999 Volume 46 Issue 7 Pages 722-726
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe sinter-diffusion bonding method of assembled inner and outer green compacts consists of same compositions except for lubricants based on Fe-Cu-C materials was investigated. Green compacts added some amount of zinc stearate as lubricants for compaction show large thermal expansions at higher temperature more than 873K in the rising process during sintering in RX-gas atmosphere. Applying this phenomena, high bonding strength can be obtained by assembling inner green compacts consist of Fe-Cu-C added of zinc stearate as lubricants with outer green compacts consist of same compositions as inner except for lubricants materials which do not contain any zinc, and by sintering in RX-gas atmosphere.View full abstractDownload PDF (2467K) -
Mitsuru Nakamura, Noriaki Chida, Hiroaki Furuno, Hiroshi Kubo, Ko-ichi ...1999 Volume 46 Issue 7 Pages 727-734
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis study investigated to effect of atmospheric gas (N2-H2 base) influenced by each properties on sintered carbon steel. Especially, it measured the hydrogen concentration, the amout of flowing gas, the change of dew point and investigated to influence by 2 types binder and enrich gas flowed by used atomized powder and reduced powder. As a result, the change of dew point influenced to worst values of mechanical properties in all conditions, and it occurred to decarburization above -40°C. Mechanical properties of high dew poit specimens was lower values than that of commercial base specimens. In addition, adding enrich gas was occurred to carburization at surface of specimens. Most variable condition of each properties on sintered carbon steel was maintained to under -50°C of dew point, 3vol% H2 concentration and the amout of flowing gas was 350l/min constant.View full abstractDownload PDF (5795K) -
Noboru Nakayama, Kotaro Hanada, Naoya Sukegawa, Toshio Sano, Hiroyuku ...1999 Volume 46 Issue 7 Pages 735-740
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn the present study, the thin film forming of pure aluminum powders is carried out by a dynamic compaction method. The influence of processing parameters on the density, mechanical properties and microstructures of compacted powders is investigated. The control of stress wave is also attempted in order to obtain a high compacting stress due to the superimpose of stress waves. The dynamic powder compaction is carried out by an electromagnetic induction method. This method allows easy control of stress pulse. Two kinds of punches with a straight shape and a sudden increase in cross section are used for the dynamic powder compaction. Pure aluminum powders of 37, μm in average are used as a raw material for the compaction. The compactions are carried out at room temperature in air. A density measurement shows that the compacted Al powders have a relative density of 0.90-0.97. As the stress has increased with a superimpose of the incidence stress wave and reflection stress wave in using the punch with the sudden increase in cross section, the bending strength of the compacted powders is stronger than the one in using the punch with a straight shape.View full abstractDownload PDF (2111K) -
Hiroshi Yamamoto, Gaku Obara1999 Volume 46 Issue 7 Pages 741-745
Published: July 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSr-La-M ferrite fine particles were prepared by mechanical compounding using the planetary ball-mill and subsequent heat treatment. This experiment was carried out to investigate the effect of La2O3 additive on the magnetic properties of Sr-M ferrite fine particles. The optimum condition of making Sr-La-M ferrite fine particles and some properties of typical specimens are as follows; chemical composition: SrO.5.75Fe2O3; additive: 1.0wt%aLa2O3; planetary ball-mill condition: 300rpm×1h; heating condition: 1050°C×1h in air; magnetic and lattice constant are σs=88.3×10-6Wb⋅m/kg, HCJ=476kA/m, Tc=459°C and lattice constant a=5.880×10-10m, c=23.01×10-10m.View full abstractDownload PDF (1603K) -
Masatoshi Otake, Kenji Isobe, Toshimi Kosugi, Koichi Tsuchiya, Minoru ...1999 Volume 46 Issue 7 Pages 746-751
Published: July 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSTi-Ni shape memory alloys were fabricated by a pulse current sintering process from two types of starting powders prepared through different processes: mechanical alloying of TiH and Ni powders mixture and dehydrogenation(MA powder), and pre-mixed of Ti and Ni powders (mixed powder).
The MA powder was composed of mainly TiNi phase and a small amout of Ti2Ni and TiNi3 phases. The composition of this powder remained unchanged after the pulse current sintering at 973-1173K for 300s, while the relative density of 100% was attained for the sintering body. On the contrary, the pulse current sintering of the mixed powder at 1273K for 60-300s, led to a distinguished compositional change and the relative density of 100%. The TiNi3 phase in the sintered body could be removed on the condition of longer sintering period or by heat treatment at 1273K for 18ks; however, the Ti2Ni phase could not be removed. The composition and the thermal characteristics (Ms=318K) of these sintered bodies were found to be almost the same as those of commercially available Ti-Ni shape memory alloys.View full abstractDownload PDF (6389K) -
Takashi Kanou, Takahiro Sawaguchi, Atunori Kamegawa, Hitoshi Takamura, ...1999 Volume 46 Issue 7 Pages 752-756
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIt is reported that the Bi metal/ceramics composites can show PTCR properties at the melting point of Bi metal of about 270°C. This materials have a few advantages such as low resistivity and high PTCR properties, but there is the problem that the resistivity doesn't coincide with the original value after the cycle measurement. This will be originated from Bi metal rearrangement during melting. Further densifications of ceramic matrix phase will overcome this problem. The purpose of the present study is to prepare high-density sample by hot-pressing, and to clarify the relationship between resistivity-temperature characteristics and microstuructures in obtaining the optimum conditions of hot-pressing.
The relative density of hot-pressed 0.55Bi-0.45SrBi4(Ti0.95Nb0.05)4O15 with using fine Bi metal reached more than 99% and its resistivity of nearly 10-1Ωm at room temperature remains unchanged after cycle measurement. In addition, the magnitudes of PTCR effect reaches 7 order of magnitude, and resistivity-temperature curve also remains unchanged even after 3rd measurements.View full abstractDownload PDF (2015K) -
Masanori Tajima, Koji Hayashi1999 Volume 46 Issue 7 Pages 757-766
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe microstructural change during the formation of semiconductive FeSi2 (β-phase) from FeSi (e-phase) and Fe2Si5 (α-phase) two metallic compounds by isothermal heating at 1123 K in Mn-doped Fe-66.7at%Si alloys which were prepared by both melting-solidification and sintering processes was firstly investigated, paying attention to the following peculiar phenomenon; some ε-phase particles were covered with β-phase layer and the others were not in solidified alloy. Secondly, the cause for the acceleration of β-phase formation rate by the addition of Pd was investigated. It was found that there were two kinds of α-phases; the one (α ?? ) decomposed to β- and Si phases by the eutectoid reaction and the other (αs) did not by the heating for up to 180 ks. The formations of two kinds of band-shaped regions which were caused by both these two kinds of α-phases and the eutectic reaction of the liquid were judged to be the causes for the peculiar phenomenon. The acceleration of β-phase formation rate by addition of Pd was attributed to both the increase of the α, -phase amount ratio and the acceleration of the eutectoid reaction of a, phase. In the consideration on non-shrinkage of α-phase particles inside test piece, a new hypothesis of "vacancy extinction in the core of core-rim structure" which stops the vacancy supply to the core/rim interface or the reaction at the core/rim interface was proposed.View full abstractDownload PDF (15268K) -
Hiroshi Terada, Toshiyuki Ido, Hideo Goto1999 Volume 46 Issue 7 Pages 767-771
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe prepared Ag-sheathed Bi system tape by the stuff with compression molding powder-in-tube method. Ag-sheathed tape of Bi system superconductors were studi-ed for sample with nominal composition of Bi1.8Pb0.4Sr2Ca2.2Cu3Oy. The critical current density of sample apparently depended on the thickness of the tape and increased markedly with decreasing tape thickness. The maximum value of the critical current density of sample 6.1×105A/cm2 at 6 K in zero magnetic field was achieved in a tape with 0.3 mm thickness and at 77K were 1.4×104A/cm2 in zero magnetic field.View full abstractDownload PDF (2656K) -
Katsuyoshi Kondoh, Yoshinobu Takeda1999 Volume 46 Issue 7 Pages 772-779
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSEffect of PVA binder content on characteristics of granulated aluminum alloy powders produced by fluidized-bed wet type granulator was investigated. The granulated powder had a mean particle size of 75-100μm and showed spherical shape. Flowability was remarkably improved and it was equivalent to that of iron powder. Apparent density of granulated powder was decreased compared with that of raw one because of both the uniform particle size distribution and spherical shape. Dimensional tolerance of green compacts obtained by using granulated powder was much improved compared with that in using raw powder because weight of powders in die fill was stabilized due to the excellent flowability.View full abstractDownload PDF (4610K) -
Katsuyoshi Kondoh, Yoshinobu Takeda, Ryuzo Watanabe, Hitoshi Hashimoto1999 Volume 46 Issue 7 Pages 780-786
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCompaction behaviors of wet granulated aluminum powder were examined by uni-axial die compaction and effects of rearrangement and plastic deformation on them were analyzed by using Cooper-Eaton equation. Based on calculation results and structurelmorphology of granulated powder, new compaction model for granulated powder, which consists of three compaction mechanisms; macro-rearrangement, micro-rearrangement and plastic deformation, and modified equation were proposed in this study. It indicated that a macro-rearrangement was a dominant factor on compaction behavior of granulated powder and the modified equation was adaptive enough to analyze compaction behavior.View full abstractDownload PDF (526K) -
Tomikatsu Kubo, Shoichi Fujino, Akihiro Kishida, Hiroshi Sakai, Nobuya ...1999 Volume 46 Issue 7 Pages 787-791
Published: July 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe low temperature oxidation of the xZnFe2O4-(1-x)Fe3O4 solid solution in air was studied based on X-ray diffraction (XRD), magnetization and Mössbauer spectroscopy measurements. The phase separation on nanometer scale to the Zn-rich phase and Fe-rich phase begins in the samples with 0.25≤x≤0.80 during oxidation in air at 300°C. Following the increase in oxidizing time, the compositional fluctuation proceeds accompanied by the oxidation of Fe(II) ions to Fe(III) ions in the Fe-rich phase. The Fe-rich phase, in which undetectable Zn may exist, can be oxidized to γ-Fe2O3 after a long periods of oxidation at 300°C in air, because the separated Fe-rich phase has a nanometer size. Finally, we obtained the ZnFe2O4/γ-Fe2O3 nanocomposite. On the other hand, the precipitation of α-Fe2O3 occurs in the sample with x≤0.10 after the oxidation in air at 300°C. This may came from the fact that the separated Fe-rich phase is as large as the bulk Fe3O4 and the oxidation of Fe3O4 to γ-Fe2O3 can not take place after a certain period of annealing in air.View full abstractDownload PDF (349K)
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