粉体および粉末冶金
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
16 巻, 4 号
選択された号の論文の4件中1~4を表示しています
  • 小菅 皓二
    1969 年 16 巻 4 号 p. 169-182
    発行日: 1969/08/25
    公開日: 2009/05/22
    ジャーナル フリー
  • 小川 清也, 中島 友円, 上原 康男, 小林 治, 白崎 高保, 坂本 重顕
    1969 年 16 巻 4 号 p. 183-189
    発行日: 1969/08/25
    公開日: 2009/12/04
    ジャーナル フリー
    Oxidation of fine powders of Mn-Zn Ferrites prepared by the ‘co-precipitation’ method has been presented.
    Differential thermal analysis showed a sharp exothermic peak corresponding to ‘hematite’ precipitation. A temperature of the peak, Tp, depends upon a heating rate φ and a crystallite size, ε, expressed by a simple relation:φ⋅ε∝exp(-Q/kTp), where Q=2.1±0.2eV. The relation indicates that the specific reaction rate is inversely proportional to crystallite size and that its temperature dependence is expressed by an activation process of 2.1eV. The size dependence could be explained by the oxidation of the total surface area and the temperature dependence by cation diffusion in Fe-poor Mn-Zn ferrite. Isothermal oxidation processes were studied by X-ray diffraction analysis and explained qualitatively by the same mechanism as the above relation.
  • 山家 菱, 貞広 孟史
    1969 年 16 巻 4 号 p. 190-195
    発行日: 1969/08/25
    公開日: 2009/12/04
    ジャーナル フリー
    Changes in various properties of TiC-Ni-Mo alloys during sintering process were observed to study the effect of carbon content on the structure of intermediate phase formed around the TiC grain. The results are as follows.
    (1) The wetting of TiC by Ni-Mo alloy were improved by increasing carbon content.
    (2) With an increase in the carbon content, the carbide grains changed from angular to spherical forms. The grain size and the thickness of the intermediate phase of carbide were reduced.
    (3) The structure of the intermediate phase were examined by X-ray microanalyser as follows. These results were demonstrated clearly by the presence of a molybdenum-rich zone at the edge of carbide coupled with a molybdenum-free region in the core of grains.
    As the carbon content in TiC-Ni-Mo alloys increases, this molybdenum-rich zone was found to approach the core boundary, and the diffusion of nickel from the liquid nickel into the intermediate phase and the solution of carbide into the nickel binder were reduced.
  • Fe-Cr-C系に関する研究
    矢島 郁夫, 村山 肇
    1969 年 16 巻 4 号 p. 196-202
    発行日: 1969/08/25
    公開日: 2009/05/22
    ジャーナル フリー
    Physical and mechanical properties of sintered Fe-Cr-C alloys have been studied. The results obtained were as follows:
    (1) A maximum tensile strength of about 52 kg/mm2 were obtained for some sintered Fe-Cr-C alloys.
    (2) Hardness increases with an increase of Cr content, their maximum value being at 2.0wt% of Cr.
    (3) Wear resistivity of Fe-2 Cr-1C sintered alloys was about 1/2-1/3 times to that of the conventional pistonring cast iron.
    (4) Heat resistivity of Fe-2 Cr-1C sintered alloy indicates micro vickers hardness number of 150-250 at 60°C and tensile strength of about 30 kg/mm2 at 600°C.
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