Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
Volume 48, Issue 8
Displaying 1-18 of 18 articles from this issue
  • Koji Koike, Misato Mizuhashi, Etsuro Sugimata, Shoichi Nasu, Kentaro O ...
    2001 Volume 48 Issue 8 Pages 675-678
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    A new compound has been synthesized by iodine intercalation on Bi2212 single crystal under the existence of Pd. Its lattice parameter along c-axis was 18.44Å shorter than that of I1Bi2Sr2CaCu2Oy (19.09Å). Fluorescence X-ray analysis microscope data showed that only I2 was intercalated in Bi2212. The temperature dependence of the in-plane nomal resistivity was metallic-like, while the out-of-plane nomal resistivity was almost temperature independent. The transition temperature (onset) of this intercalated new compound was 85 K in both directions. The thermogravimetric curve showed weight loss of 3.9%.
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  • Mari Miyauchi, Daisuke Iwanaga, Takako Hibi, Yukie Nakano, Takeshi Nom ...
    2001 Volume 48 Issue 8 Pages 679-684
    Published: August 15, 2001
    Released on J-STAGE: December 04, 2009
    JOURNAL FREE ACCESS
    Effect of annealing, in an oxidizing atmosphere after sintering, on the electrical properties and microstructure of (Ba, Ca)(Ti, Zr)O3-based (BCTZ-based) multilayer ceramic capacitors with Ni internal electrodes has been studied. In the case of the dielectric layer thinner than 2μm, insulation resistance greatly increased by annealing, and the layer between the Ni-electrodes was observed to be single grain. After annealing, there was an interface of 0.4 nm between dielectric material and Ni-electrode. The composition of interfaced region was different from the BCTZ-based dielectric.
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  • Hoshiteru Nozawa, Takagimi Yanagitani, Keijiro Hiraga, Keishi Nakano, ...
    2001 Volume 48 Issue 8 Pages 685-691
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    The effect of doping Silicon on the high-temperature deformation of superplastic Yttrium Aluminum Garnet (YS-YAG) was studied under conditions of uniaxial tension. In the preceding paper, the elongation and strain rate of YAG ceramics was described as having decreased by the addition of Si as a sintering aid. This was one of the reasons that the grain size of Si-doped YAG ceramics greatly increased compared with that of non-doped YAG ceramics during deformation. Creep deformation of Y2O3-excess YAG, with an average grain size of 1.6μm, was shown to have an elongation of over 210% (=εn) at 1773 K. Accordingly, we prepared Si-doped Y2O3-excess YAG ceramics (YS-YAG) having the above two chemical composition, and developed YAG materials having two characteristics; remarkable grain growth and elongation. The deformation of YS-YAG reached 200% (=εn) at 1773 K under a constant stress creep tensile test, in spite of the grain size of YS-YAG changed from 1.5 μm to 6μm during deformation.
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  • Junjiro Takekawa
    2001 Volume 48 Issue 8 Pages 692-696
    Published: August 15, 2001
    Released on J-STAGE: July 12, 2010
    JOURNAL FREE ACCESS
    It has been known that the Cu powder compacts often swell when sintered in H2 gas, therefore the densification and the strength of the sintered compacts are limited to low levels. In this study 0.1-1.5 mass% ZrO2 fine powder was mixed with Cu powder in order to prevent the swelling during sintering. These mixed powders were sintered in both H2 and vacuum atmospheres at 850°C-1050°C.
    It was shown that the addition of ZrO2 fine powder was extremely effective on the prevention of the swelling of the Cu compacts during sintering, and the high densification was obtained. The reason why ZrO2 fine powder prevent the swelling durring sintering could be explaned as follows: it may delay the formation of isolated pores by slowing down the sintering of Cu powder particles and simultaneously make the deffusion pathes for reaction gaseous. It was also shown that the most effective amounts of ZrO2 fine powder on the densification of Cu powder increased with increasing sintering temperatures. The addition of ZrO2 fine powder improved the tensile strengths of sintered Cu compacts because of its function to make the grains fine.
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  • Isao Endo, Ryosei Okuno, Hideki Satake, Isamu Otsuka, Hiroshi Yamamoto ...
    2001 Volume 48 Issue 8 Pages 697-702
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    In this paper, characteristics of the amorphous soft-magnetic alloy powders fabricated by the new atomization process "SWAP; Spinning Water Atomization Process" with both of high quenching rate and possibility of the mass-production are presented.
    In the equipment, gas-atomized droplets are rapidly quenched by the effect of centrifugal force of the high speed spinning water. The speed, the depth and the temperature of the spinning water influence the quenching rate of droplets. Fe-Si-B alloy powders produced by this method were in the amorphous state at particle size up to 300μm in diameter and exhibited good soft-magnetic properties and very low oxygen contents of about 100-200ppm. The powder surface observed by SEM was smooth and their morphology was spherical for finer particle and rather flat for larger particle, suitable for forming consolidated powder core. Therefore, "SWAP" is expected to be useful for high production yield of amorphous powder and to be available for development of amorphous powder cores.
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  • [in Japanese]
    2001 Volume 48 Issue 8 Pages 704
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
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  • Masanobu Izaki
    2001 Volume 48 Issue 8 Pages 705-709
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    Magnetic Iron oxide film with the closeness of stoichiometric Fe3O4 (magnetite) has been prepared onto a non-conductive quartz glass substrate maintained at 293 K by light-assisted solution chemical reaction in an aqueous solution containing iron (III) nitrate hydrous and dimethylamineborane (DMAB). Fe3O4 film with smooth surface of 3.2nm in root-mean-square-roughness (Rms) was grown at 293 K and showed 480emu/cc in saturation magnetization and 150 Oe in coercive force. Raising the solution temperature gave the increase in Fe3+ constituent and decrease in saturation magnetization. The film prepared at 333 K was identified as a mixture of Fe3+, O2-, and OH- constituents and showed no magnetization. The resistivity ranging from 0.23 to 450Ωcm was obtained depending on solution temperature and was higher than that for the bulk material. This will be attributed to the non-stoichiometry of Fe2+/Fe3+ ions in Fe3O4 film.
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  • Tae-Yobu Kim, Tomoyasu Taniyama, Yoshitaka Kitamoto, Yohtaro Yamazaki, ...
    2001 Volume 48 Issue 8 Pages 710-714
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    The magnetic properties of the superparamagnetic Co-substituted Bi-DyAJIG (BiDy2CoxAlyFe5-x-yO12: 0≤x≤0.2, 0≤y≤1.1) nanoparticles were investigated. On the basis of the magnetic data, it is inferred that the magnetic moments of Dy ions cant from those of the iron ions. The canting angle was estimated to be 53°, which is larger than that previously observed in the sputtered films. The reason of the canting is possibly the surface and/or size effect of the nano-size garnet particles. The Co substitution was found to be effective to increase the coercive-force of the nanoparticles for magnetic recording storage media. The bifurcation temperature of zero-field-cooled (ZFC) and field-cooled (FC) magnetizations is also increased by the Co substitution. The ZFC and FC magnetization curves for the BiDy2CoxAly, Fe5-x-yO12 nanoparticles suggest that Co substitution enhances magnetic anisotropy of the nanoparticles, which is in accordance with increase in coercive-force Hc.
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  • Shintaro Ishiwata, Masaki Azuma, Takashi Saito, Shuji Kawasaki, Mikio ...
    2001 Volume 48 Issue 8 Pages 715-718
    Published: August 15, 2001
    Released on J-STAGE: December 04, 2009
    JOURNAL FREE ACCESS
    Single crystals of CaFeO3 have been synthesized at high pressure of 4.5 GPa with a mixture of KClO4, NaCI and CaCl2 as flux and oxidizing agent. The temperature dependence of the resistivity showed a metal-insurating transition at 295 K, corresponding to the charege disproprotionation. A screw-spin type antiferromagnetic transition was observed at 115 K. These results indicated that the crystals were free from oxygen defect. Energy-dispersive powder X-ray diffraction study with synchrotron radiation at high pressure revealed that a moisture was necessary to crystal growth of CaFeO3.
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  • Hiroshi Yamamoto, Yasuaki Ozaki
    2001 Volume 48 Issue 8 Pages 719-723
    Published: August 15, 2001
    Released on J-STAGE: December 04, 2009
    JOURNAL FREE ACCESS
    Ba-La-Co M-type ferrite fine particles were prepared by the chemical coprecipitation process and a heat treatment. The chemical reagents used for the experiment were FeCl3⋅6H2O, BaCl2.6H2O, LaCl3⋅7H2O, and CoCl2.6H2O. The chemical coprecipitation process was applied to the samples having the formula {(BaO⋅n/2(Fe2O3))100-x-y(La2O3)x (CoO)y (n=7.0-12.0, x=1.0-10.0, y=1.0-10.0) the solution containing Ba2+, Fe3+, La3+, and Co2+ was poured into solution of NaOH (pH=13.0). The precipitated products were boiled for 2hs and they were carefully washed with water and dried. The obtained fine particles were heated at 950 to 1100°C for 2hs in air to obtain the single phase of Ba-La-Co M-type ferrite fine particles. The best magnetic properties were observed for the sample with the composition of {(BaO⋅n/2(Fe2O3))94.0(La2O3)3.0(CoO)3.0. The maximum values of magnetic properties were as follows: σ5=87.1×10-6 Wb⋅m/kg(69.3 emu/g), σr=42.9×10-6Wb⋅m/kg (34.1 emu/g), HCJ=469.5 kA/m (5.82 kOe) and TC= 456.4°C.
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  • Hiroshi Yamamoto, Kazuya Maekawa, Yasuhiro Sakai
    2001 Volume 48 Issue 8 Pages 724-729
    Published: August 15, 2001
    Released on J-STAGE: December 04, 2009
    JOURNAL FREE ACCESS
    An experiment was carried out to investigate the effects of a Zn-organic-compound as a new reducing agent, and SiO2 and CaO additives, on the magnetic and physical properties of SrFe2-hexagonal ferrite (W type). It was found that the magnetic properties of SrO⋅9.0Fe2O3 were considerably improved by adding 0.1 wt% of Zn-organic-compound, 0.3 wt% of SiO2, and 0.7 wt% of CaO together. The optimum conditions for making magnets and the prime properties of typical specimens are as follows: Based on chemical analysis: Composition: Sr2+0.930Si4+0.097 Ca2+0.169Zn2+0.007Fe2+1.307, Fe3+16.265O27; semisintering conditions (S.S.C.): 1350°C×4.0h in nitrogen gas atmosphere; drying condition (D.C.): 200°C×4.0 h in air; sintering condition (S.C.): 1170°C×1.5 h in nitrogen gas atmosphere. Magnetic and physical properties are as follows: Jm=0.468(T). Jr=0.433(T), HcJ=175(kA/m), HcB=161(kA/m), (BH)max=32.70(kJ/m3), Tc=500.9(°C), HA=1401 (kA/m), KA=3.28, and nB=30.0μB, a=5.757×10-10(m), c=33.41×10-10(m), and c/a=5.804.
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  • Koichiro Morimoto, Kazunori Igarashi, Eiichiro Niizuma, Ryoji Nakayama
    2001 Volume 48 Issue 8 Pages 730-735
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    We investigated influences of original alloy microstructure on magnetic properties of the isotropic HDDR (hydrogenation-decomposition-desorption-recombination)-treated Nd126Fe79.0Co2.4B6.0 powder by comparing two types of starting materials, i.e., the strip cast (SC) alloy and the conventional book-mold cast (BMC) alloy. It was found that utilizing the SC alloy can achieve better I-H loop squareness, and consequently higher remanence in the final powder. The powder prepared from the SC alloy exhibits a more uniform grain structure of the recombined Nd2Fe14B phase, which is thought to be closely related to its good loop squareness. The effect of using the SC alloy is supposed to be attributed to the complete elimination of α-Fe particles before the HDDR treatment.
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  • Chieko Sasaki, Taku Murase, Takeshi Nomura
    2001 Volume 48 Issue 8 Pages 736-741
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    As for the manufacturing process of ferrite, it is of prime importance to uniformly fill granules into dies and to obtain uniform green compact. In this study, the effect of granule size on the filling and compaction behaviors has been studies for MnZn ferrite with special reference to the green microstructure. In the case that granule size is large, filled density of the die-leg decrease with the decrease of leg width of the die. On the contrary, in the case of smaller granules, the pressure at which the granules start to deform is lower than that of the larger granules, and the difference of green density between upper side and lower side shows an increase. The bending strength of green compact becomes large as granule size becomes small.
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  • Kei Hirata, Setsuo Yamamoto, Hiroki Kurisu, Mitsuru Matsuura, Takanori ...
    2001 Volume 48 Issue 8 Pages 742-747
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    Reactive sputtering using an Electron-Cyclotron-Resonance microwave plasma was introduced to prepare Co containing ferrite thin-film media at substrate temperatures lower than 150°C without post oxidation process. The ferrite thin-films deposited on glass substrate had a perpendicular magnetic anisotropy, high coercivity of about 240 kA/m and very smooth surface. The ferrite thin-film media annealed in magnetic field showed a large perpendicular magnetic anisotropy, perpendicular coercivity of 258 kA/m and perpendicular loop with the high squareness of 0.82.
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  • Kei Hirata, Setsuo Yamamoto, Hiroki Kurisu, Mitsuru Matsuura, Takanori ...
    2001 Volume 48 Issue 8 Pages 748-752
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    Co-containing ferrite thin films were successfully deposited on organic flexible substrates by the reactive sputtering method using-an electron cyclotron resonance microwave plasma at a temperature lower than 150°C. The ferrite thin films had an amorphous-like structure, perpendicular magnetic anisotropy and high perpendicular coercivity of about 170kA/m. The perpendicular coercivity increased with increasing substrate thickness. Inserting SiO2 underlayer between organic flexible substrate and ferrite thin films enhanced the perpendicular coercivity.
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  • Hiroki Tetsukawa, Masashi Meguro, Takuya Ito, Makoto Inoue, Yasukazu M ...
    2001 Volume 48 Issue 8 Pages 753-757
    Published: August 15, 2001
    Released on J-STAGE: July 12, 2010
    JOURNAL FREE ACCESS
    The oxidation stability and structure of acicular fine Fe-Co particles have been investigated. The oxidation stability in the high temperature range is improved with the increase of Co content in the metal particles. It is observed that the shape of the cross section of Fe metal particles without Cc is distorted and the surface oxide layer shows diffuse diffraction spots. On the contrary the shape of the cross section of Fe-Co particles is approximately circular and the surface oxide grows to be coherent with the core α-Fe suggesting that the amount of the defects of the surface oxide layer reduces. Based on these results, it is found that the improvement of the oxidation stability by addition of Co is attributed to the morphology of the particles and the structure of the surface oxide layer around the core α-Fe. The oxidation stability also depends on the size of metal particles.
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  • Katsushi Kusaka, Jyunya Taguchi, Tetsuya Kondo
    2001 Volume 48 Issue 8 Pages 758-763
    Published: August 15, 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
    The objective of this study is mainly to elucidate the effect of N addition on DC magnetic properties of Fe-Cr type PM stainless steels bearing Cr of 9-24wt%. The magnetic measurement was practically carried out about specimens before and after the heat-treatment upto 1173 K in a N atmosphere. Finally, these data were evaluated in the terms of degradation of magnetic properties by N absorption, together with residual pores.
    The results obtained were summarized as follows:
    (1) Fe-Cr alloys, heated at 673 K in a N gas show higher magnetic induction (B)/maximum permeability (μm) and also, lower coercive force (Hc) in the vicinity of Cr: 12wt%, as well as as-sintered ones.
    (2) When Fe-Cr alloys are heated upto 1173 Kin a N gas, the magnetic properties, especially μm, are wholly degraded, and the peak values mentioned-above are shifted to Cr rich region.
    (3) For the degradation ratio, ΔB/B increases abruptly at 1073 K corresponding to N absorption, while Δμmm linearly increases with the rise of heat-temperature though fairly scattered due to being structure-sensitive.
    (4) Roughly evaluated including HIPed materials, magnetic properties are degraded with the rise of amount of N, austenite-former, in relation to ferrite-former and also, non-magnetic Cr constituent.
    (5) Specimens sintered at higher temperature tend to absorb small amount of N and hence, show better magnetic properties, although the correlation of N content to sintered density (ρ) is not apparently larger.
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  • 2001 Volume 48 Issue 8 Pages 765
    Published: 2001
    Released on J-STAGE: May 22, 2009
    JOURNAL FREE ACCESS
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