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Volume 17, Issue 1
Displaying 1-6 of 6 articles from this issue
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[in Japanese], [in Japanese]1970 Volume 17 Issue 1 Pages 5-12
Published: June 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (1908K) -
Hiroshi Itô, Hiroki Fukunaga, Masaru Nakayama1970 Volume 17 Issue 1 Pages 13-18
Published: June 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTungsten-chromium sintered compacts were hot-pressed at 1450°C for 30 min in graphite moulds. Mechanical properties and high-temperature oxidation resistance of sintered compacts were tested. And also the improvement of oxidation resistance by small additions of Al and Si was tested.
Results obtained are summarized as follows.
(1) The density of the hot-pressed specimens were more than 95% of the theoretical value.
(2) The hardness of the sintered compacts was HRC 56.6-63.0, higher than the hardness of tungsten.
(3) Transverse rupture strengths of 30-40kg/mm2 were obtained.
(4) The addition of Cr (>30 wt%) was found to improve the oxidation resistance.
(5) (W-30 Cr)-Si alloy was suitable for tungsten-base high temperature materials.View full abstractDownload PDF (3865K) -
1970 Volume 17 Issue 1 Pages 18
Published: 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (32K) -
Sintering in the Binary System of TaC-ZrCShigetomo Matsuo, Michihiko Horie, Yoshio Jumi1970 Volume 17 Issue 1 Pages 19-24
Published: June 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCarbides of Groups IVb, Vb, and VIb metals have high melting point, high hardness, and good electrical conductivity as well as good thermionic emissivity. Moreover, they exhibit high mechanical strength at elevated temperatures.
Among these, ZrC, HfC, TaC and their solid solutions are important as high temperature materials because of their high melting points. But, since they have poor sinterability, few precise details are known about the powdered mixture or solid solution. This study, in a series of studies on TaC base materials for incandescent filaments, is aimed at development of sintered materials resistant against thermal shock.
In this report the sintering properties in the binary system TaC-ZrC were studied by using a vacuum hot-pressing apparatus, since it was considered that the acceleration of the densification seems to control the properties, especially the mechanical properties of the sintered material.View full abstractDownload PDF (389K) -
Ryuzo Watanabe, Masanori Hinata, Yoshimichi Masuda1970 Volume 17 Issue 1 Pages 25-28
Published: June 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe sintering of iron-copper (17 vol%) powder compacts has been studied on the basis of the sintering characteristics of iron powder compacts. The sintering was carried out in various heat-treatment programs in which A3 transformation and melting of copper were taken into account. The dilatometric measurements were made during sintering and the microscopic structures were examined on some sintered specimens also. The sintering behaviors of iron-copper (17 vol%) alloy powder were similar to those of iron below the melting point of copper, that is, the discontinuous grain growth at A3-transformation inhibited farther shrinkage in both α and γ ranges. The discontinuous grain growth also prevented the shrinkage in the presence of liquid copper. This effect was remarkable when the specimen had been pre-sintered in the a range.View full abstractDownload PDF (4010K) -
Shu Yamazaki, Michiyasu Komatsu1970 Volume 17 Issue 1 Pages 29-34
Published: June 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn an attempt to improve the ductility of doped tungsten, effects of Co addition on some properties of powder and sintered bar have been studied.
Simultaneous adding Co together with the common doping agents, Al2O3, SiO2 and K2O affected the average particle size of the reduced powder. Cc reduced the average particle size. Additions of 0.01-0.06 weight % of Co emphasized the restraining effect of Al2O3-doping on grain growth. Fractographs of sintered bars by means of a scanning electron microscope were characteristic and showed many small spherical pores and large tubelar pores. But fra-ctographs of sintered bars containing 0.3% Cc showed straight crystal boundaries and large spherical pores. The high concentration of these pores is attributed primarily to vaporization of doping additives or their products, and it is considered that these pores are closely related to the doping effect on the recrystallization of wires.View full abstractDownload PDF (5305K)
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