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 42, Issue 8
Displaying 1-7 of 7 articles from this issue
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  • Numerical Simulation for Friction Mechanism of Powder Bed Using 2-Dimensional Distinct Element Method
    Shinichi Yuu, Toshihiko Umekage, Yutaka Kawasaki
    2005 Volume 42 Issue 8 Pages 528-536
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.528
    JOURNAL FREE ACCESS
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    The motion of particles under the shear stress has been numerically simulated using 2-dimensional Distinct Element Method. The calculated results well describe the stick-slip phenomena caused by the friction in the particle bed. The results also show that the motions governed these phenomena are particle rotations which arise the slip motion from the static stick state of the particle bed. These motions of particle rotations are transmitted to the fairly deep inside area of the particle bed due to the particle-particle interaction.
    Based on these calculated results we also have obtained the friction loop which is qualitatively in good agreement with the data measured by Nasuno et al (Physical Review E, 58 Part B, 2161-2171 (1998)). However the calculated friction coefficient of particle bed is about 30% of measured value by Nasuno et al. The main cause seems to be the difference of the clearances between the cover plate particles and the bed particles from the real state in the powder bed.
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  • Numerical Simulation for Friction Mechanism of Powder Bed Using 3-Dimensional Distinct Element Method and Experimental Verification
    Toshihiko Umekage, Shinichi Yuu, Kenji Katsuki
    2005 Volume 42 Issue 8 Pages 537-545
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.537
    JOURNAL FREE ACCESS
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    The motion of particle bed under shear stress has been numerically simulated using 3-Dimensional Distinct Element Method. The calculated results quantitatively well describe the stick-slip phenomena caused by the friction between a shear plate and particle bed. Homogeneous and closed configuration of contact particles in the friction plane is important for the prediction of stick-slip phenomena. The present results confirm that the motions governing these phenomena are particle rotations which suddenly arise the slip motion from the static stick state of the particle bed. The results also show that the close packed particles at stick state change to loose packed particles at the slip state due to the shear force. This phenomenon corresponds to the solid to liquid phase transition in the solid and the thin liquid film frictions.
    The friction loop calculated based on these results is fairly in good agreement with the measured data. The friction forces for example during the stick-slip can be correctly obtained using the friction coefficients along the friction loop.
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  • Improvement in Throughput of Centrifugal Classification System Using an Almost Rigidly Rotating Flow
    Yoichi Tsuchida, Koichi Nakabayashi, Yohei Morinishi, Tomohito Suzuki
    2005 Volume 42 Issue 8 Pages 546-557
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.546
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    This paper proposes new high-throughput classifiers of FOF-CB and FOF-MCM types for an accurate wet centrifugal classification of low mass concentration slurry. The new classifications make use of an almost rigidly rotating through-flow that is formed by only the feed suspension. The classification performance of both types has been studied by numerical simulations of fluid and particle motions, and the classifiers have proved to be effective. The FOF-CB type classifier is able to attain high-throughput batch-type classification by partitioning the collection region of a fine product into two regions. The FOF-MCM type classifier, on the other hand, can be a high-throughput continuous-type classifier by extracting coarse and medium products continuously from the housing and by separating the collection region of a fine product into two regions. However, the medium product does not become the classified product because it includes both fine and medium fractions.
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  • Synthesis of β-Tricalcium Phosphate and Calcium Hydroxyapatite Using Waste Incineration Fly Ash
    Hidekazu Tanaka, Nobutoshi Kan, Ryozi Hino
    2005 Volume 42 Issue 8 Pages 558-563
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.558
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    β-tricalcium phosphate (Ca3(PO4)2: β-TCP) and calcium hydroxyapatite (Ca10(PO4)6(OH)2: Hap) were synthesized from waste incineration fly ash (Fa). The Fa was washed with H2O and heated at 1000°C in air as a pretreatment. The pretreatment increased CaO molar fraction by the dissolution of NaCl and KCl as well as the decomposition of CaCO3 and Ca(OH)2. The β-TCP was obtained by the reaction of pretreated Fa and dicalcium phosphate dihydrate (CaHPO4·2H2O: DCPD) at 1000°C in air. The best molar ratio DCPD/(Ca in pretreated Fa) for synthesis of β-TCP was found to be 1.5. The Hap was prepared using β-TCP obtained from Fa by treating it in NaOH solution at 90°C for 18h. When the pretreated Fa was treated in H3PO4 solution at pH=9.0 and 85°C, the CaO in Fa were completely dissolved to form Hap. Based on these results, we suggest that the Fa is a useful calcium source for the synthesis of β-TCP and Hap.
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  • Synthesis of Functional Nanoparticles by Thermal Plasmas
    Takayuki Watanabe
    2005 Volume 42 Issue 8 Pages 564-572
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.564
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    Attractive processing techniques for nanoparticle synthesis by thermal plasmas have been developed, because atmospheric pressure plasmas offer unique advantages. These advantages include high enthalpy to enhance reaction kinetics, high chemical reactivity, oxidation and reduction atmospheres in accordance with required chemical reactions, and rapid quenching (106K/s). These advantages have accelerated the advances and demands in plasma processing for nanoparticle synthesis. In this paper, the generation of plasmas under atmospheric pressure and the characteristics are reviewed. Furthermore, plasma processing for nanoparticle synthesis of oxides, nitrides, carbides, and intermetallic compounds is reviewed to clarify the generation mechanisms.
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  • A New Improvement Technology of Fine Powder by Utilizing Adhesive Property
    Shigenobu Hatano
    2005 Volume 42 Issue 8 Pages 586
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.586
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  • Annual Report of Working Group on Measurement and Analysis of Powder Properties, 2004
    [in Japanese]
    2005 Volume 42 Issue 8 Pages 588
    Published: August 10, 2005
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.42.588
    JOURNAL FREE ACCESS
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