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 62, Issue 6
June
Displaying 1-10 of 10 articles from this issue
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Paper
Memorial Lecture of JSPM Award
  • Synthesis of Novel Functional Oxide Materials using High Pressures
    Takashi SAITO, Yuichi SHIMAKAWA
    2015 Volume 62 Issue 6 Pages 289-296
    Published: June 15, 2015
    Released on J-STAGE: June 30, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.289
    JOURNAL OPEN ACCESS
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    High pressure synthesis is a powerful technique for searching novel functional oxide materials. Perovskite oxides have rather dense crystal structure and hence are easily stabilized under pressures. We have been searching for novel A-site ordered perovskite oxides by a high pressure synthesis method, and have discovered a variety of compounds with interesting properties. Here we report on the synthesis and physical properties of new A-site-ordered perovskite oxides AMn3V4O12 (A = Na, Ca, La) with Mn in a square planar coordination. As the A-site cation changes from Na+ to Ca2+ and to La3+, the Mn/V sites are doped site-selectively, and local-spin magnetism by Mn ion and metallic transport property by V ion coexist. Spin-glass behavior is induced by mixed-valence Mn2.33+ in NaMn3V4O12, while unusual non-collinear 60°-spin structure of Mn2+ spins is found for LaMn3V4O12.
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Review
  • —New Possibility in Powder Metallurgy—Creation of High Mechanical Performance Materials by Harmonic Structure Design
    Mie OTA, Kei AMEYAMA
    2015 Volume 62 Issue 6 Pages 297-301
    Published: June 15, 2015
    Released on J-STAGE: June 30, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.297
    JOURNAL OPEN ACCESS
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    Grain refinement is known as the one of the effective methods to improve strength of metallic materials. However, it is accompanied by lower ductility due to early stage plastic instability. Therefore, strength and ductility are in trade-off relationship. Our research group has proposed “Harmonic Structure Design”, having bimodal grain size distribution, which permits to achieve a combination of high strength and high ductility through Severe Plastic Deformation/Powder Metallurgy (SPD/PM) process. The Harmonic Structure has a peculiar feature that it consists of a three-dimensional continuous and inter-connected network of fine-grained regions. Moreover, although, the microstructure is heterogeneous at micro-scale, it is homogeneous at the macro-scale. The benefits of Harmonic Structure can be observed in the applicability of this microstructural design to a wide range of metallic materials, irrespective of the nature of material, phase, or crystal structure. FEM analysis estimated that the geometrically continuous fine-grained network structure prevents local strain concentration, leading to high ductility in the harmonic structure designed materials.
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Paper
  • Wear Property of Harmonic-Structured Material with High Speed Steel and Mild Steel Produced by MM/SPS Process
    Hiroshi FUJIWARA, Yuki TSUZUKI, Hiroyuki MIYAMOTO
    2015 Volume 62 Issue 6 Pages 302-307
    Published: June 15, 2015
    Released on J-STAGE: June 30, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.302
    JOURNAL OPEN ACCESS
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    The harmonic-structured material that consists of a network fine grain region with a high speed steel and a dispersed coarse grain region with a mild steel was fabricated prepared using a mechanical milling and spark plasma sintering process. The wear properties of harmonic-structured materials with the high speed steel volume fraction of 15.4 to 30.0 % were evaluated by the wear test of the ball-on-disk type. The wear property for Vickers hardness of the harmonic-structured material with the high speed steel volume fraction of 30.0 % is superior to various materials such as ferrous, non-ferrous materials and ceramic materials. The wear surfaces of the harmonic-structured materials were observed by the scanning electron microscope and laser microscope. The wear surface observation of harmonic-structured materials reveals that the wear property of the harmonic-structured material depends on the volume fraction of the high speed steel network region. The superior wear property of harmonic-structured material needs approximately 30.0 % of high speed steel volume fraction.
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  • Experimental Studies on Ball Milled Wasted Glasses and Their Self-hardening Properties
    Masataka KAMITANI, Mitsunori KONDO, Atsushi NAKAHIRA
    2015 Volume 62 Issue 6 Pages 308-312
    Published: June 15, 2015
    Released on J-STAGE: June 30, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.308
    JOURNAL OPEN ACCESS
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    In order to construct the resources circulation society in Japan, we investigated the material recycling methods on huge amount of wasted glasses. Because wasted glasses could be chemically activated by ball milling method, and we tried to modify up to the environmental clean-up materials. The self-hardening phenomenon was confirmed from ball milled wasted liquid crystal display panel glasses after alkaline treatment. The characterization of the hardened samples was carried out. These results showed that the self-hardening induced mechano-chemical effects will open a new method for wasted glass utilizations.
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Short Note
  • Thermoelectric Properties of FeSi2 Thermoelectric Conversion Modules Sintered with Ag Joint Plates by Spark Plasma Sintering Method
    Hironori SUZUKI, Shinya WARAGAI, Yukihiro HIGASHI, Yuki TAKASAWA, Taku ...
    2015 Volume 62 Issue 6 Pages 313-317
    Published: June 15, 2015
    Released on J-STAGE: June 30, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.313
    JOURNAL OPEN ACCESS
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    To achieve high performance of thermoelectric conversion module, it is important that the contact electric resistance between thermoelectric element and electrode is decreased. The manufacturing method to perform sintering of FeSi2 powder and joining of the sintered body with Ag metal plates at the same time was examined by using SPS(spark plasma sintering) method. The Ag plates were successfully joined to FeSi2 element by this process. In addition, it was able to lower the resistance of thermoelectric conversion module because the contact electric resistance between the FeSi2 element and the Cu electrode was decreased by joining Ag plates. The thermoelectric conversion modules with various element heights were produced by this process, and the performance of the modules was evaluated under several temperature differences. The most suitable thermoelectric module height, 5 mm, was decided by investigating relations of the module height and the performance. The FeSi2 thermoelectric conversion module consisting of 50 pairs of p-n elements was produced using an element with 5 mm height, and the performance was measured. As a result, the maximum electric power of FeSi2 thermoelectric conversion module of 50 pairs was 1.70 W in the condition of heating temperature at 873 K and/or cooling temperature at 293 K.
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