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Volume 28, Issue 7
Displaying 1-6 of 6 articles from this issue
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[in Japanese], [in Japanese]1981 Volume 28 Issue 7 Pages 239-244
Published: October 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (4055K) -
Hiroshi Utsugi, Atsushi Endo, Noboru Suzuki, Nobuko Hanaoka, Mitsuhiko ...1981 Volume 28 Issue 7 Pages 245-250
Published: October 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWhen the hydrophobic fine powders were dosed into water, they spread over the water surface as an oil does, whereas they were easily dispersed into acetone. These hydrophobic fine powders were dosed into the aqueous acetone solutions with several concentrations, and the surface tensions of them were the values between that of water and acetone. The surface tension of the solutions into which the powders easily dispersed was determined. The surface energy of these powders was estimated from the thermodynamic consideration on the interface between powder and solution. The surface energy was also estimated for the powders which were easily dispersed into water, whereas they were collected into the interface between water and hexane after adding the hexane to these aqueous suspensions and shaking these suspensions.View full abstractDownload PDF (1694K) -
Osamu Yamaguchi, Akihiko Moriyama, Kiyoshi Shimizu1981 Volume 28 Issue 7 Pages 251-256
Published: October 25, 1981
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe reaction of equimolar mixtures between Li2CO3 and amorphous SiO2 has been studied by means of DTA, X-ray diffraction and thermogravimetric techniques. The reaction was found to proceed in seven stages: Li2CO3+SiO2(amorphous)→Li2O⋅SiO2+CO2 (1)
Li2CO3+2SiO2(amorphous)→Li2O⋅2SiO2+CO2 (2)
2Li2CO3+SiO2 (amorphous)→2Li2O⋅SiO2+2CO2 (3)
Li2CO3+Li2O⋅2SiO2→2(Li2O⋅SiO2)+CO2 (4)
2Li2O⋅SiO2+SiO2(quartz, cristobalite)→2(Li2O⋅SiO2) (5)
2Li2O⋅SiO2→Li2O⋅SiO2+liquid (6)
Li2O⋅2SiO2→Li2O⋅SiO2+liquid (7)
The main part of the overall reaction concerning with the decomposition of Li2CO3 was best expressed by the contracting cube equation and the apparent activation energy was determined as 36.3 kcal/mol. This activation energy can be assigned to the overall reaction (1)-(3).View full abstractDownload PDF (279K) -
Hisashi Suzuki, Koji Hayashi1981 Volume 28 Issue 7 Pages 257-259
Published: October 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe transverse-rupture strength of WC-(5.5-20)%Co alloys coated with titanium carbide by CVD was studied to make clear the cause of the strength decrease of those alloys.
It was found that the strength of coated alloys is controlled by the total thickness of coated layer and the layer containing η-phase, in accordance with the result of Stjernberg. Therefore, it is considered that the strength decrease is unavoidable. Some discussions to check the strength decrease have been given.View full abstractDownload PDF (2553K) -
Hisashi Suzuki, Koji Hayashi, Yoshio Takashima1981 Volume 28 Issue 7 Pages 260-263
Published: October 25, 1981
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe transverse-rupture strength of WC-β-Ni alloy (β; WC-TiC solid solution) having nitrogen, which was prepared by using WC-TiC-TiN solid solution or TiN powder, was mainly studied at room temperature. The alloy was vacuum-sintered at 1693K.
It was found that the strength of nitrogen contained alloy was apt to decrease, owing to the pore formation during sintering; However, after eliminating the pore by HIP, it became superior, in particular in the alloy prepared by using solid solution powder, to that of the nitrogen free alloy, resulting from the sharp refinement of carbonitride grains.View full abstractDownload PDF (1571K) -
Tadahiko Watanabe1981 Volume 28 Issue 7 Pages 264-268
Published: October 25, 1981
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThis paper describes, firstly, the effects of the sintering temperature on the mechanical properties of TiB2-5%TaB2-1%CoB, TiB2-5%TaB2-1%NiB, TiB2-5%TaB2-1%FeB and TiB2-5%TaB2-1%Co alloys; secondary, the effects of the amount of binders on those of TiB2-5%TaB2-CoB, TiB2-5%TaB2-NiB and TiB2-5%TaB2-FeB alloys. The results were as follows:
1. CoB was the best binder for TiB2-TaB2 based cermets. The TiB2-5%TaB2-1%CoB alloys sintered at the temperature of 1700 to 1900°C for 28 min under 200 kg/mm2 in a vacuum had the transverse rupture strength of 95 kg/mm2, and scarcely had pores.
2. In the cases of CoB, NiB and FeB binders, TiB2-TaB2 based cermets had a solid solution between TiB2 and TaB2. However, TiB2-5%TaB2-1%Co sintered body scarcely had the solid solution between TiB2 and TaB2.
3. The binder phases of TiB2-5%TaB2-1%CoB alloy and TiB2-5%TaB2-1%FeB alloy may be CoB and FeB, respectively. The binder phases of TiB2-5%TaB2-1%NiB alloy may consist of NiB and monoclinic Ni4B3 and unknown phases. Also TiB2-5%TaB2-1% CoB alloy may have the binder phases of CoB and Co2B.View full abstractDownload PDF (3107K)
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