Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 59, Issue 1
January
Displaying 1-11 of 11 articles from this issue
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Paper
  • Synthesis of Mullite Using Fine Sand Generated in Recycling Process of Waste Foundry Sand
    Taro Atsumi, Seisho Take, Hiroyoshi Matsunuma, Toshihisa Kumakura
    2012 Volume 59 Issue 1 Pages 3-7
    Published: 2012
    Released on J-STAGE: February 08, 2012
    DOIhttps://doi.org/10.2497/jjspm.59.3
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    Fine sand generated in a recycling process of waste foundry sand is used as raw material for cement. In order to find more effective use for the fine sand, we attempted to synthesize mullite using the sand as a silica source. Self-propagating high-temperature synthesis was carried out by adding thermite powder, a mixture of aluminum and iron oxide (III) with a molar ratio of 2:1, to the fine sand. A mixture containing 20 wt% of fine sand was heated to a maximum temperature of approximately 1660 K by an exothermic reaction, and the major products of this reaction were mullite and iron. The maximum combustion temperature of a mixture with more than 20 wt% of fine sand decreased with an increase in the fine sand content. In these cases, not all of the fine sand reacted: the reaction products were corundum, hematite, mullite and iron.
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  • Lithium-Ion Conducting Properties of a Hot-pressed 75Li2S·5P2S3·20P2S5 (mol%) Glass
    Yuji Ooura, Nobuya Machida, Syunji Kinoshita, Muneyuki Naito, Toshihik ...
    2012 Volume 59 Issue 1 Pages 8-13
    Published: 2012
    Released on J-STAGE: February 08, 2012
    DOIhttps://doi.org/10.2497/jjspm.59.8
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    A cold-pressed pellet of ion-conducting glassy powders generally shows lower conductivity than a monolithic bulk glass with the same chemical composition. This degradation of ion conductivity of the cold-pressed pellet would be caused by interfacial resistances between glassy particles. In order to improve the conductivity of glassy pellet, we tried a hot-press method for the glassy powder in the chemical composition 75Li2S·5P2S3·20P2S5 (mol%) at around its glass-transition temperature. The hot-pressed pellet under the conditions: pressure 200 MPa, heating temperature 483 K, heating rate 5 Kmin-1 and heating time 1 h, showed high ion conductivity at 298 K, σ298K=1.5×10-3 Scm-1, and the activation energy Ea= 33 kJmol-1. Those ion conducting properties of the hot-pressed pellet were superior to those of a pellet cold-pressed at 200 MPa (σ298K= 6.1×10-4 Scm-1, Ea= 38 kJmol-1).
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Special Issue: New Development of High Performance ElectronicComponent Materials Processing Technology
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  • Effect of Reducing Atmosphere on AlN Ceramics Sintered by Millimerter Wave-HIP Combined Sintering
    Kyohei Yamashita, Yoshihisa Kogo, Takashi Teranishi, Hidetaka Hayashi, ...
    2012 Volume 59 Issue 1 Pages 17-21
    Published: 2012
    Released on J-STAGE: February 08, 2012
    DOIhttps://doi.org/10.2497/jjspm.59.17
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    The effect of reducing atmosphere on yttria dispersed AlN ceramics sintered by millimeter wave-HIP combined sintering was investigated. The specimens were sintered by millimeter wave (MMW) heating under nitrogen reducing atmosphere containing 3 vol% hydrogen followed by post-HIP treatment at 1700°C for 0.5 h under nitrogen pressure of 190 MPa. The relative densities to the theoretical one saturated at the first MMW heating over 1700°C. Thermal conductivities of AlN ceramics sintered by MMW heating under heavily reduced atmosphere with nitrogen were higher than that through MMW heating under normally reduced atmosphere. The thermal conductivity increased with decreasing the yttria additive amount and with increasing the sintering temperature. The optimized yttria dispersion amount was 1 wt% in the MMW heating at 1800°C for 0.5 h. Relative density and thermal conductivity increased by post-HIP treatment. The optimized yttria dispersion amount shifted from 1 wt% to 3 wt% after post-HIP treatment.
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Review
  • Lattice-Defect Control for High-Performance Bismuth-Based Ferroelectric/Piezoelectric Crystals
    Yuuki Kitanaka, Yuji Noguchi, Masaru Miyayama
    2012 Volume 59 Issue 1 Pages 22-28
    Published: 2012
    Released on J-STAGE: February 08, 2012
    DOIhttps://doi.org/10.2497/jjspm.59.22
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    In ferroelectric/piezoelectric materials, lattice defects with a high density often deteriorate their properties, and their essential nature does not appear. Recently, Bi-based ferroelectrics have attracted much attention as a Pb-free material from the environmental and economical points of view. However, high-quality single crystals of Bi-based ferroelectrics have not been obtained over the past 60 years because of the defect-related problems, and their fundamental properties are shrouded in a veil. In the present article, we show the crystal growth technique under high oxygen pressure as an effective method for growing high-quality Bi-based ferroelectric single crystals.
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Paper
  • Preparation of MgAl2O4 Spinel Powder by Corrosion Reaction Synthesis
    Daichi Sasaki, Osami Seri
    2012 Volume 59 Issue 1 Pages 29-33
    Published: 2012
    Released on J-STAGE: February 08, 2012
    DOIhttps://doi.org/10.2497/jjspm.59.29
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    Electrochemical attempts have been made to obtain fine powders of MgAl2O4 spinel by applying metallic corrosion in ethanol with addition of chloride ions as catalyst. The obtained corrosion product, which contains mixture of metallic ions and ethoxides, was hydrolyzed and fired. The sintered powders of MgAl2O4 were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The MgAl2O4 spinel powders of 30∼100 nanometer size particle aggregation were obtained by firing above 1273 K. A new spinel synthesis method which was easy and low cost was proposed and considered in the electrochemical point of view, and its merits and demerits for production were enumerated.
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