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 29, Issue 11
Displaying 1-5 of 5 articles from this issue
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  • The Compressive Crushing of Brittle Materials in a Powder Bed
    The Effect of Feed Size on the Production of Fine Particles
    Yoshiteru KANDA, Tadaaki OYAMADA, Ryoji NAKAYAMA, Takayuki MATSUO
    1992 Volume 29 Issue 11 Pages 824-830
    Published: November 10, 1992
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.29.824
    JOURNAL FREE ACCESS
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    Roller mills have come to be actively used for the production of fine particles. In this paper, stress conditions in a roller mill were simulated by the slow compression of powder beds between parallel platens, and compressive crushing of brittle materials in powder beds was also carried out to fundamentally study the grinding mechanism of a roller mill. The effect of the feed size on the production of fine particles was investigated when the applied load and the mass of the feed were constant. The crushing energy is defined as the energy input in a powder bed. The specific crushing energy to produce fine particles (the crushing resistance) was experimentally calculated. The samples used were limestone, quartz, and quartz glass.
    The following results were obtained:
    (1) When the applied load and the mass of feed were constant, the feed size with a minimum deformation of powder beds was observed.
    (2) The size distribution of the crushed product changed depending on the kinds of solids, and the difference in the size distributions increased with the decrease in the feed size.
    (3) The feed size with the same mass of micronized product was observed and found to have a certain range. This range was enlarged with the decrease in the size of the product.
    (4) The specific crushing energy to produce fine particles changed with the kinds of solids and feed size.
    (5) Then, in order to produce micronized particles for a higher energy utilization by a roller mill, it is necessary to evaluate the grindability of materials in advance.
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  • New Method for the Preparation of Polyamide Coated Aluminium Nitride Powder
    Junko TAKADA
    1992 Volume 29 Issue 11 Pages 831-837
    Published: November 10, 1992
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.29.831
    JOURNAL FREE ACCESS
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    Aluminium nitride (AlN) powders are thermodynamically unstable in an aqueous system. Polyamide (Nylon) coating of the carbothermic method AlN powders can confer a great degree of water-resistibility on them. However, nylon coated powders have high organic contents including chloroform and show bad formability. Moreover, this method cannot be applied to direct nitridation AlN powders.
    In this study, we succeeded in nylon coating both direct nitridation and carbothermic method AlN powders by a new preparation method, carrying out polymerization at the solid-liquid boundary after fixing a monomer on the surface by drying. As a result, the nylon coated powders have low organic contents with no chloroform and show good formabilty.
    In addition, the sintered bodies of the nylon coated powders which were prepared with oxidation treatment of the direct nitridation AlN powders were found to contain Al2Y4O9 and to have high thermal conductivity.
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  • Study of the Shape Separation of Fine Particles Using Fluid Fields
    Dynamic Properties of Irregular Shaped Particles in Wet Cyclones
    Shigehisa ENDOH, Hitoshi OHYA, Chihiro IKEDA, Kaoru MASUDA, Shigeyuki ...
    1992 Volume 29 Issue 11 Pages 838-844
    Published: November 10, 1992
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.29.838
    JOURNAL FREE ACCESS
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    In order to apply hydrodynamic fields to the shape separation of fine particles, the dependencies of dynamic properties of particles in a cyclone on the particle shape were discussed. Glass beads, glass powders, silica sands and mica particles in a 10-100μm size range were classified into five fractions by wet cylclones. The equivalent diameters of classified particles were measured by a free settling method, and the geometric parameters were obtained from SEM microphotos. The Stokes diameters in free settling were in agreement with the mean values which were estimated for an ellipsoid and a thin disc to settle in random orientation. On the other hands, Stokes diameters in the cyclones were smaller than those in free settling. The discrepancy between these diameters was large especially for flaky mica particles, suggesting that a cyclone can be used to separate flaky particles from blocky ones.
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  • New Carbon Materials
    Michio INAGAKI
    1992 Volume 29 Issue 11 Pages 845-853
    Published: November 10, 1992
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.29.845
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  • [title in Japanese]
    1992 Volume 29 Issue 11 Pages 862-865
    Published: November 10, 1992
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.29.862
    JOURNAL FREE ACCESS
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