Journal of the Society of Powder Technology, Japan
Online ISSN : 1883-7239
Print ISSN : 0386-6157
ISSN-L : 0386-6157
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Volume 37, Issue 11
Displaying 1-7 of 7 articles from this issue
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  • Property Control of Acicular γ-Fe2O3 Particles by Synthesis Conditions of Starting Goethite
    Haruki KUROKAWA, Mamoru SENNA
    2000 Volume 37 Issue 11 Pages 788-795
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.788
    JOURNAL FREE ACCESS
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    Magnetic properties of acicular γ-Fe2O3 particles for magnetic recording media derived from goethite particles are regulated directly by controlling the morphology of goethite particles. The shape and magnetic properties of acicular γ-Fe2O3 by oxidizing weakly alkaline solution are examined by varying conditions: the initial Fe2+ concentration, the neutralization molar ratio in the seed reaction, and the partition of the rate of Fe2+ consumption either by the seed reaction or by the growth. Possible ranges of control are 200-300nm for the particle sizes, and 8 to 14 for the aspect ratio, while the S. D. of the aspect ratio between 2.5 to 5. Consequently, desirable acicular γ-Fe2O3 with a higher SQ and a lower SFD in the hysteresis curve can be synthesized.
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  • In-situ Measurement of Angle of Repose of Coal Fly Ash at Elevated Temperatures
    Kayoko MORISHITA, Hisashi NISHIKOHRI, Jun-ichiro HAYASHI, Tadatoshi CH ...
    2000 Volume 37 Issue 11 Pages 796-799
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.796
    JOURNAL FREE ACCESS
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    A new apparatus was designed for in-situ observation of bulk powder cone formation on a disk and the measurement of angle of repose of cone at elevated temperatures. It was applied to detect the change in adhesive property of coal fly ashes with temperatures between 300 and 1073K. Regardless of types of fly ash generated from different raw coals, the angle of repose increased with elapsed time after the deposition and reached a constant value which was independent of the feed rate. Accordingly, the maximum angle of repose, φrmax, was uniquely defined as a function of temperature, gas atmosphere as well as the other properties of fly ash. The φrmax's for three types of fly ashes were found to increase rapidly with temperature between 770-870K, which is much lower than their fusion temperatures. The results also suggested that acid-leachable metallic species contribute to an increase in φrmax whereas unburned carbon reduces φrmax.
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  • Scaling Law of Fine Particle Classification by Almost Rigidly Rotating Flow
    Koichi NAKABAYASHI, Yoichi TSUCHIDA
    2000 Volume 37 Issue 11 Pages 800-807
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.800
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    Scaling law of fine particle classification by a centrifugal system was studied in the present work. The centrifugal system accurately classifies fine particles suspended in a liquid (water) at a low concentration by applying an almost rigidly rotating through-flow between the housing- and core-walls of a rotating double-walled container. We performed calssification experiments under various conditions by changing classifier size, feeder, true relative density and size of feed powders, and Ekman and Rossby numbers. Consequently, we found that the scaling law is such that the ratio of cut-off size to the length scale of the fluid or particle motion (characteristic length of the classifier) is determined as a function only of the centrifugal-effect parameter which is the ratio of centrifugal force to drag force exerting on a particle.
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  • Stratospheric Ozone Depletion
    Yasunobu IWASAKA
    2000 Volume 37 Issue 11 Pages 808-818
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.808
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  • How to Produce the Latest Food Particles
    Teruo YOSHIDA
    2000 Volume 37 Issue 11 Pages 819-825
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.819
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  • [title in Japanese]
    2000 Volume 37 Issue 11 Pages 826-829
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.826
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  • [title in Japanese]
    [in Japanese], [in Japanese]
    2000 Volume 37 Issue 11 Pages 830
    Published: November 10, 2000
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.37.830
    JOURNAL FREE ACCESS
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