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 8, Issue 5
Displaying 1-3 of 3 articles from this issue
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  • Structure and Property of Binder Phase of WC-Co Composition
    Tamotsu Fukatsu
    1961 Volume 8 Issue 5 Pages 183-194
    Published: October 25, 1961
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.8.183
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    In order to clarify the sturctures and the properties of binder phase in cemented tungsten carbide alloy with cobalt, physical properties such as lattice constant, Curie temperature and magnetization of γ-Co solid solution containing up to 15% WC by weight have been studied. Based on these results, the change of the binder phase in WC-5.5% Co composition during the sintering has been first observed. Then, the effect of the various cooling rate from melt on the kinds of alloy phases, and also the structue of γ-Co phase of the Co rich-WC alloys have been investigatd by the method of microscope, X-ray diffraction and thermomagnetic techniques. The results obtained were as follows. By slow cooling, ry or (γ+WC) phases, and by rapid cooling (γ+η) phases appeared on the samples of 5-35% WC-Co alloys. But (γ+η) phases were unstable, and so by annealing, (γ+η) phase changed to stable (γ+WC) phase. These results mentioned above could be described consistently by the double phase diagram containg unstable η phase shown in Fig.8. The process of decomposition of η phase and the simultaneous change of γ phase were also invetigated.
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  • Effect of Impurities on Grain-Boundary of Ferrites and their Electrical Resistivities. Part II.
    Tsuneo AKASHI
    1961 Volume 8 Issue 5 Pages 195-209
    Published: October 25, 1961
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.8.195
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    As described in Part I, the resistivity of ferrites is greatly increased by simultaneous addition of CaO and SiO2. In order to clarify the effect of impurities, various investigations have been carried out. The high resistivity thus obtained decreases with frequency. This suggests that the ferrites have an inhomogeneous dielectric structure consisting of poor-conducting layers separating relatively goodconducting grains. It was confirmed by autoradiograph and other techniques that the impurities were almost localized near the grain boundaries to form poor-conducting layers. The substance of grain boundary is considered as mixed oxide of the ferrite and the impurities, represented by (Ca1-xSixOγ)i-y(Ferrite)y. In fact, it was found that at certain composition of this series, the resistivity was extremely high and varied with firing conditions in the same mann eras the ferrite containing the impurities. It was concluded that the grain-boundary had profound effect on the resistivity of ferrite.
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  • Creep in Powder Metallurgy Products
    F.V. Lenel
    1961 Volume 8 Issue 5 Pages 210-219
    Published: October 25, 1961
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.8.210
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