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 31, Issue 2
Displaying 1-6 of 6 articles from this issue
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  • [title in Japanese]
    [in Japanese]
    1984Volume 31Issue 2 Pages 39-44
    Published: February 25, 1984
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.31.39
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  • Hydrogen Oxidation Behavior and Structure of Gas-Diffusion Electrodes Consisting of WC-PTFE System
    Junichi Hojo, Katsumasa Nakahara, Masashi Matsumoto, Akio Kato
    1984Volume 31Issue 2 Pages 45-50
    Published: February 25, 1984
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.31.45
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    Porous gas-diffusion electrodes containing WC catalyst (particle size: 0.07 or 1.2μ) were prepared by the sintering of WC-PTFE powder mixture, and their hydrogen oxidation activity was investigated at the potential below +300 mV(vs. NHE) in 1N-H2SO4 aqueous solution under latm-H2 atmosphere at 25°C with emphasis on the effect of the electrode structure. It was confirmed that there is the most appropriate content of PTFE. It was found that hydrogen oxidation is governed by the electrical conductivity of electrode, i.e., the current-collecting ability. The increase in molding pressure of electrode film accelerated the hydrogen oxidation, which may be due to the coupling of the realization of a moderate hydrophobic action by PTFE and the increase in the electrical conductivity of electrode.
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  • Properties of Ti(C, N)-Mo Sintered Compacts
    Hisashi Suzuki, Hideaki Matsubara
    1984Volume 31Issue 2 Pages 51-55
    Published: February 25, 1984
    Released on J-STAGE: December 04, 2009
    DOIhttps://doi.org/10.2497/jjspm.31.51
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    The microstructures, mechanical properties at room temperature of TiC0.7N0.3- and TiC0.5N0.5-(5-40)vol%Mo alloys vacuum-sintered at 1973K were mainly studied.
    It was found that microstructures of TiC0.7N0.3- and TiC0.5N0.5-Mo alloys consisted of carbonitride and Mo phases, when Mo content exceeded about 20 and 10 vol%, respectively, and the structure became finer with increasing nitrogen and Mo contents in the alloys. In the alloys sintered in nitrogen, Mo2C phase was apt to form and the amount depended on nitrogen pressures as well as the nitrogen content of alloys. The transverse-rupture strength and hardness of vacuum-sintered alloys were higher in the alloy with lower nitrogen content, and the former increased and the latter decreased with increasing Mo content, respectively.
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  • Microstructures and Mechanical Properties of WC-Cr3C2-15%Co Cemented Carbide
    Hisashi Suzuki, Kei Tokumoto
    1984Volume 31Issue 2 Pages 56-59
    Published: February 25, 1984
    Released on J-STAGE: December 04, 2009
    DOIhttps://doi.org/10.2497/jjspm.31.56
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    Some properties of WC-15%Co alloy were studied as a function of additional amounts of Cr3C2, and carbon contents of the alloy.
    It was found that solid solubility limits of Cr in binder were about 4 and 11% in high and low carbon alloys, respectively. When the additional amount of Cr3C2 was excess beyond the solubility limit of Cr, M7C3 type carbides which crystallized were observed in the structure. Total amounts of Co and W dissolved in M7C3 increased in high carbon alloy, and the amount of M7C3 was in the same way under a fixed amount of Cr3C2. The transverse-rupture strength of the alloy was not almost affected by Cr3C2 addition, within the additional amount up to the value nearly corresponding to the solubility limit of Cr in binder. The solubility limit of Cr increased by rapid cooling the specimen after sintering.
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  • High Oxygen Pressure Synthesis and Magnetic and Electrical Properties of LixM1-xCo2 O4(M=Co, Zn)
    Masao Ohashi, Masahiko Shimada, Mitsue Koizumi
    1984Volume 31Issue 2 Pages 60-66
    Published: February 25, 1984
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.31.60
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    The cubic spinel type oxides, LixM1-xCo2O4 (M=Co, Zn), were synthesized under high oxygen pressures. From the result of crystallographic and magnetic properties, the cation distributions of the present systems were determined to be (Li+x Co2+1-x) [Co1+2-x Co4+x](0 ?? x ?? 0.4)and (Li+ 0.22 Zn2+ 0.66 Co2+0.12)[Co1+ 1.78 Co4+ 0.22]O4. Electrical resistivity data indicate that the electron transport in these systems occurs owing to a hopping mechanism between Co+1 and Co4+ ions located at octahedral site.
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  • Synthesis and Magnetic Properties of RMn2Si2(R=Y, Nd, Gd)and YNi2Si2
    Hiroyasu Kido, Takeshi Hoshikawa, Masahiko Shimada, Mitsue Koizumi
    1984Volume 31Issue 2 Pages 67-69
    Published: February 25, 1984
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.31.67
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    A series of the RMn2Si2 (R=Y, Nd and Gd) were prepared by heating the mixed powder with the stoichiometric composition in an evacuated silica tube, and YNi2Si2 was synthesized under high temperature and pressure conditions. The crystal structure of these compounds was closely identified with the bodycentered tetragonal ThCr2Si2 type structure. Results of magnetic measurements showed that all RMn2Si2 (R=Y, Nd and Gd) compounds were antiferromagnetic with TN=514K for YMn2Si2, 386K for NdMn2Si2 and 477K for GdMn2Si2. YNi2Si2 was Pauli-paramagnetic indicating that the 3d shells of Ni atoms were fully occupied by the electrons transferred from Si atoms.
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