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 31, Issue 3
Displaying 1-15 of 15 articles from this issue
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  • [title in Japanese]
    Yoshitaka KUWAHARA
    1994 Volume 31 Issue 3 Pages 145
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.145
    JOURNAL FREE ACCESS
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  • The Effect of Surface Characteristics of Silica Particles on Electrorheology
    Akiko KAWAI, Kunio UCHIDA, Kunio KAMIYA, Akihiro GOTOH, Shigenobu HAYA ...
    1994 Volume 31 Issue 3 Pages 146-150
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.146
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    The effect of the surface characteristics of silica particles on Electrorheology (ER) was investigated with a suspension which contains monodispersed silica particles in silicon oil. Two types of adsorbed water exist at the silica surface: one is dehydrated below 200°C (free water) and the other above 200°C (bound water). It was found that free water was inevitable due to the ER effect, and there was an appropriate amount of free water for an optimum ER effect. Silica surface was treated with cetanol. Cetanol-treated silica has less bound water than untreated silica. The amount of free water on the cetanol-treated silica was controlled by vacuum-drying and exposure to saturated water vapor pressure. The cetanol-treatment of silica lowered the ER effect. In the less bound water on the cetanol-treated silica, the control of free water didn't change the ER effect. A direct relationship was not found between the ER effect and current density.
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  • Uniform Dispersion of Fine Particles in a Magnetic Fluid and its Evaluation
    Masanori HORIZOE, Ryuzo ITOH, Keishi GOTOH
    1994 Volume 31 Issue 3 Pages 151-156
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.151
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    Particles confined in a thin horizontal layer of magnetic fluid were uniformly dispersed by applying a vertical magnetic field. The particle arrangements were observed both in experiments and in computer simulations of two dimensions. The regularity of particle dispersion was defined by the mean value of areas of the Voronoi polygons and its variance, R=‹α›2/σ2, for the evaluation of the particle arrangements. The clusters of particles were virtually made by uniformly swelling all of the particles. The distribution of the cluster size can be utilized for detail evaluation of the particle arrangement. The regularity of the particle dispersion depends on the repulsive force acting between the particles. The uniformity of particle dispersion increases with the intensity of the magnetic field and the initial concentration of the particles.
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  • Characterizing the Electrostatic Charging of Polymer Particles by Impact Charging Experiments
    Tatsushi MATSUYAMA, Hideo YAMAMOTO
    1994 Volume 31 Issue 3 Pages 157-162
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.157
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    Impact charging experiments were systematically conducted using four kinds of polymers for impacting particles and three metal targets with different work functions in all of their combinations. The equilibrium charges were independent of the work function of the metal target and were almost constant for each polymer. Discussion of the results of this experiment suggested that the charge relaxation in the particle separating process determimes the impact charge if this impact charging is generated under atmospheric conditions. One important reason for studying this charge relaxation process is to understand the particle charging mechanism. Furthermor, these discussions and experimental results suggested that the characteristic which decides the amount of charge generation, in charge generation in the dry powder processes etc., is the dielectric constant of the polymer material of which the particle consists.
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  • Characterization of Magnetic Powders by the Electromagnetic Induction Method
    Yukio FUJIHARA
    1994 Volume 31 Issue 3 Pages 163-169
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.163
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    A new method has been developed for nondestructive testing of the property of magnetic fine powders.
    It was found that the appreciate value was closely related to the property of the magnetic fine powders. Here, the appreciate value is defined as the peak value of the derivative of normalized impedance with frequency.
    The following results were obtained:
    (1) The appreciate value of the ferromagnetic, paramagnetic and diamagnetic powders are respectively, closely related to the magnetic susceptibility.
    (2) The appreciate value for the mixture of binary powders is closely related to the composition of the mixture.
    (3) The appreciate values increased with increase in the amount of powder packed in the vessel.
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  • The Separation of Mixed Fine Powders by Electrophoresis
    Mutsuo SANDO, Atsuya TOWATA, Yoshinori UWAMINO, Yoshitaka KUWAHARA
    1994 Volume 31 Issue 3 Pages 170-175
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.170
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    A sub-micron powder of either alumina or zirconia was separated by electrophoresis. A mixed suspension of these powders was prepared in a powder concentration of 150-200ppm at pH 5.0, where both alumina and zirconia had enough positive zeta potential to prevent from their heterocoagulation. A uniform and stable ascent flow of electrolytic solution at pH 7.4 was made, where the difference of zeta potential between alumina and zirconia was about the maximum. The ascent flow carried a fine stream of the suspension with a diameter of less than 1mm. Applying an electric field of 10V/cm perpendicular to the flow, the fine stream of suspension was divided into two fine streams. The concentration of different kind particles in each separated suspension was reduced to 1/10 of that in original mixed suspension.
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  • Synthesis and Study of the Properties of Barium Titanate Powder by the Mechanochemical Process
    Osami ABE, Yasuyuki SUZUKI
    1994 Volume 31 Issue 3 Pages 176-181
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.176
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    Synthesis of fine BaTiO3 powder through mechanochemically prepared precursors has been investigated. The precursors were prepared from Ba(OH)2·8H2O and TiO2 by wet planetary mill treatment using acetone as a liquid medium. Pseudo-cubic BaTiO3 was obtained after heat treatment of the precursors at 700°C for 3h. Anatase, rutile, Ba6Ti17O40 and other titanates did not form during thermal treatment. The BaTiO3 powder were sintered to densities more than 94% of the theoretical at 1250°C for 1h. The sintered materials showed a homogeneous microstructure consisting of fine grains less than 1μm, which was close to the optimum grain size for BaTiO3 having a high dielectric constant. The well-mixed composite precursors consisting of Ba(OH)2·xH2O and hydrous TiO2 were synthesized by the following successive processes; (1) extraction of hydrated water into the liquid media, (2) mechanochemical hyration of TiO2, and (3) alloying of dehydrated Ba(OH)2·xH2O and hydrated TiO2, for example TiO2·H2O and TiO(OH)2, although the reactions were not completed.
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  • A Study of the Internal Packing Characteristics of an Ultrafine Particle Bed by the X-ray Computed Tomography Method
    Mitsukuni MIZUNO, Genji JIMBO
    1994 Volume 31 Issue 3 Pages 182-187
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.182
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    Ultrafine particles have an extremely large external specific surface area, strong adhesive and agglomeration forces and large bed voidage exceeding 90%. Ultrafine particles were packed by means of tapping, centrifugal and compression methods, and the axial and radial distributions of voidage in the resulting beds were measured by the X-ray computed tomography (X-ray CT) method. The results of the measurements clarified the internal structures of the packed bed of ultrafine particles obtained by the above-mentioned methods, and the internal structures of the packed beds were compared with each other. It was also found that the packing characteristics depended on the structural features of the constituent particles, such as chain-like and lumpy structures.
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  • Tracking the Fine Grinding Process of Limestone Powder by BET Surface Area Measurement
    Atsushi KAMIYAMA, Sigetoshi ONO, Akira SUGANUMA, Toshitaka HAMADA
    1994 Volume 31 Issue 3 Pages 188-191
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.188
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    Limestone powder was ground with a vibration mill under various vibration rates and amplitudes. 32ml/800g-powder of methanol was added as a grinding aid. The BET specific surface area SB, of ground material increased up to the grinding limit then decreased through negative grinding.
    A characteristic time, t0, was introduced as a parameter to characterize each grinding condition. The variation of SB was correlated as a common curve of (SB-SB0) vs. t/t0. The curve was identical with that of Rittinger's law in the initial grinding phase and extended, beyond the grinding limit, to the negative grinding phase. Negative grinding also proceeds rapidly under a grinding condition in which the positive grinding proceeeds rapidly. The negative grinding rate can be roughly estimated from the rate of positive grinding in the range of Rittinger's law.
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  • Powder Properties by COMPORATOR Classification
    Adhision, Reentrainment, Aggregation and Dispersion
    Nobuo YOSHIMORI
    1994 Volume 31 Issue 3 Pages 192-195
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.192
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  • Stress-strain-time Behavior of Powders
    Hirosuke OKAMOTO
    1994 Volume 31 Issue 3 Pages 196-201
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.196
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  • Simultaneous Measurement of Particle Size and Electrostatic Charge by Using Laser Doppler Method
    Noriyoshi KAYA, Hiroyuki TSUJIMOTO, Shuji SASABE, Shinchi YOSHIKAWA, M ...
    1994 Volume 31 Issue 3 Pages 202-206
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.202
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  • NMR Study of Structures of Powdered Materials
    Shigenobu HAYASHI
    1994 Volume 31 Issue 3 Pages 207-213
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.207
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese]
    1994 Volume 31 Issue 3 Pages 214-218
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.214
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    1994 Volume 31 Issue 3 Pages 219-221
    Published: March 10, 1994
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.31.219
    JOURNAL FREE ACCESS
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