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 47, Issue 5
Displaying 1-4 of 4 articles from this issue
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  • Milling Effect of Calcium Aluminate Fine Particle Prepared by Chemical Solution Processing
    Naonori Sakamoto, Shota Watanabe, Masahito Hori, Tomoya Ohno, Desheng ...
    2010 Volume 47 Issue 5 Pages 304-309
    Published: May 10, 2010
    Released on J-STAGE: May 25, 2010
    DOIhttps://doi.org/10.4164/sptj.47.304
    JOURNAL FREE ACCESS
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    12CaO · 7Al2O3 (C12A7) composed of nanosize cage structure can clathrate oxygen radicals (O-) and has a high potential to application of strong oxidizing catalysts. In the present report, we demonstrate a fabrication route to C12A7 fine powders by Chemical Solution Deposition method and subsequent ball milling in order to enhance the catalytic reactivity. Aluminum sec-butoxide, calcium nitrate tetrahydrate, acetylacetone, 2-methoxyethanol, and nitric acid were used as raw materials. Precursor solution was dried and annealed at 900°C in O2 atmosphere. BET specific surface area of the powders revealed the C12A7 obtained by the solution process showed higher specific surface area than that of the conventional sintering process even though they were milled in the same manners. The reason for this difference may be that the disintegration effect was applied for the solution derived sample rather than the grinding.
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  • Surface Modification and Dispersion of Gas Phase Synthesized Oxide Composite Nanoparticles in Organic Solvent by Agitation Milling Process with Small Beads
    Kenji Takebayashi, Shuji Sasabe, Motoyuki Iijima, Hidehiro Kamiya
    2010 Volume 47 Issue 5 Pages 310-316
    Published: May 10, 2010
    Released on J-STAGE: May 25, 2010
    DOIhttps://doi.org/10.4164/sptj.47.310
    JOURNAL FREE ACCESS
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    Surface modification and dispersion of aggregated TiO2-SiO2 oxide composite nanoparticles (primary size : 23 nm) were carried out by agitation milling process with small beads using silane coupling agent (Phenyl-triethoxysilane) in N-Methylpyrrolidone (NMP). The dispersion behavior was controlled by the addition of a small amount of pH adjusted water in order to increase the reactivity of the coupling agent on nanoparticles surface and characterized by aggregate size distribution and the amount of chemisorbed silane coupling agent. The TiO2-SiO2 nanoparticles were dispersed down to primary particles by adjusting the milling time and additive content of silane coupling agent. The NMP suspension of TiO2-SiO2 nanoparticles was highly transparent. However, the addition of the small amount of pH adjusted water had little influence on the dispersion behavior of the aggregates.
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  • Effect of Circulating Flow on Particle Dispersion in a Stirred Vessel with Dual Paddle Impellers
    Eiji Aizawa, Takeaki Tsuda, Nobuhiro Sakano, Hironobu Imakoma, Naoto O ...
    2010 Volume 47 Issue 5 Pages 317-326
    Published: May 10, 2010
    Released on J-STAGE: May 25, 2010
    DOIhttps://doi.org/10.4164/sptj.47.317
    JOURNAL FREE ACCESS
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    Particle dispersion in a stirred vessel with dual paddle impellers was numerically investigated by a commercial CFD code. The working fluid was assumed a weak shear-thinning non-Newtonian fluid or Newtonian fluid having low viscosity (ca. 4.0 Pa · s). Particles were initially set in the lower half region in the vessel. Numerical simulations were conducted by varying rheological property, location of the impellers and discharge flow rate of impellers. Numerical results showed that the viscosity was lower near the impeller in the non-Newtonian fluid than in the Newtonian fluid due to strong shear near the forefront of impeller. Consequently, the velocity of discharge flow from impeller was larger in the non-Newtonian. Larger velocity of the discharge flow took more particles to the tank wall as compared with Newtonian fluid. The present work adopted the mean value and the standard deviation of particle concentration as particle dispersion indexes. It has been found that the standard deviation depends on particle dispersion process.
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Review
  • Mesoscale Models for Self-organization Simulation of Fine Particles in Fluid
    Masahiro Fujita
    2010 Volume 47 Issue 5 Pages 327-338
    Published: May 10, 2010
    Released on J-STAGE: February 09, 2017
    DOIhttps://doi.org/10.4164/sptj.47.327
    JOURNAL RESTRICTED ACCESS
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    This general review gives a brief description of major mesoscale models to simulate self-organization of fine particles in a fluid. The mesoscale models surveyed are Brownian dynamics, dissipative particle dynamics, moving particles semi-implicit method, fluctuating lattice-Boltzmann equation, stochastic rotation dynamics and fluctuating Navier-Stokes equation. All the models are compared with one another in terms of accuracy, applicable scope, robustness and efficiency. In addition, the author presents a unique mesoscale model and typical simulation results of self-organization of fine particles in a fluid in the field of chemical engineering.

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