Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
Search
Advanced search
OR
Browse
Search
Volume 16, Issue 5
Displaying 1-4 of 4 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
  • On the Grain Structure and Electromagnetic Properties of MnO-ZnO-MgO-Fe2O3 Ferrite Systems
    Effects of Te or MoO3 Addition
    Tsutomu Iimura
    1969 Volume 16 Issue 5 Pages 217-223
    Published: October 25, 1969
    Released on J-STAGE: December 04, 2009
    DOIhttps://doi.org/10.2497/jjspm.16.217
    JOURNAL OPEN ACCESS
    Show abstractHide abstract
    Effect of Te and MoO3 on the grain structure and electromagnetic properties of Mn-Zn-Mg-ferrites have been studied.
    (1) High permeability materials were obtained when sintered in two steps. With Te or MoO3 added, the first step was performed in air at 1350°C for 1 hour, and the second, in nitrogen at 1150°CC for 3 hours.
    (2) Uniformly, grained matrix was obtained by Te or MoO3, the addition of Te inhibitied grain growth, whereas MoO3 promoted.
    (3) Lattice constant was increased by Te but not significantly by MoO3, which could be explained by the high solubility of Te in ferrites.
    (4) Sintered density decreased markedly with the increasing To or MoO3.
    (5) Electrical resistivity increased considerably up to 0.5% addition of Te.
    View full abstract
    Download PDF (4700K)
  • Studies on the Formation of Ferrites by Hydrothermal Method
    Hidehiko Kuwamoto, Sunjiro Saito, Takeshi Takei
    1969 Volume 16 Issue 5 Pages 224-229
    Published: October 25, 1969
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.16.224
    JOURNAL OPEN ACCESS
    Show abstractHide abstract
    The crystal size of the ferrites formed hydrothermally from the mixtures of 2α-FeOOH +Zn(OH)2, 2α-FeOOH+NiO or 2α-FeOOH+Co(OH)2, was found to depend on the pH of the medium, and large cubic crystals were observable in alkaline medium, in which complex ions bearing Zn++, Ni++ or Co++ were stable.
    In case of the synthesis of these ferrites from coprecipitates, the sizes were very small and nearly independent of the pH.
    Copper ferrites were formed only from the coprecipitates or wet mixtures.
    Grain growth of the ferrites was scarcely observable during the treatments within 10 hours.
    Based on these observations, brief discussions were given on the mechanism of the formation.
    View full abstract
    Download PDF (3954K)
  • Diffusion of Boron in the Cemented Carbide (Part I)
    Katsumi Yamamura, Masami Kasai, Hiroshi Harigaya
    1969 Volume 16 Issue 5 Pages 230-234
    Published: October 25, 1969
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.16.230
    JOURNAL OPEN ACCESS
    Show abstractHide abstract
    The authors have succeeded in obtaining a new and improved tool material which is harder than any existing cemented carbide by diffusing boron on the surface of the cemented carbide or cermet, the best tool material up to the present, by means of the electrolysis in the molten salts.
    By using the test pieces of WC-Co alloy comprising cobalt of 4, 7 and 10% respectively, boron was diffused by means of electrolysis in the molten salts. We found that the surface hardness was increased by about 40 to 70%.
    This increase in hardness is due to the boride produced by the combination of boron and cobalt. The diffused layer was 40μin thickness.
    After a practical running test, it was found that the tool of this treated WC-Co alloy had the tool life three times as that of the tool without treatment and working efficiency was also increased.
    View full abstract
    Download PDF (2320K)
  • Spotted Structures in Cemented Carbides Containing Small Amount of Tantalum and Niobium Carbides
    Hisashi Suzuki, Takaharu Yamamoto
    1969 Volume 16 Issue 5 Pages 235-239
    Published: October 25, 1969
    Released on J-STAGE: December 04, 2009
    DOIhttps://doi.org/10.2497/jjspm.16.235
    JOURNAL OPEN ACCESS
    Show abstractHide abstract
    The spotted structures were confirmed by the present authors to develope in WC-Co alloys containing small amount of tantalum and niobium carbide, respectively. And, phenomena relating to the structures were investigated. The fine and coarse-grained WC-(10-20)%Co alloys having additional carbides of 0.5-2.0% were used as specimens.
    The results obtained were as follows : (1) The spotted structures appeared to be caused by the precipitation from the liquid phase enriched with tantalum carbide or niobium carbide. The enriched phase was formed probably due to the separation of liquid binder phase during the cooling of specimens. (2) Spotted phase in each alloy was identified by x-ray or electron diffraction and x-ray microanalysis as (Ta, W) C1-x or (Nb, W) C1-x, i.e., nonequilibrium phase containing abnormally large amount of tungsten. (3) The strength of the alloys was lowered markedly by the appearance of these structures.
    View full abstract
    Download PDF (6653K)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top