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Volume 21, Issue 7
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[in Japanese]1974 Volume 21 Issue 7 Pages 183-193
Published: December 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (10073K) -
Yoshinari Amano, Masahiro Kume, Kenya Motoyoshi, Sukeaki Kabayama1974 Volume 21 Issue 7 Pages 194-199
Published: December 25, 1974
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe influence of porosity and the additional elements on the discharge machining characteristics of Cu-70 wt% W (Cu-52 vol o W at full density) type alloys (electrode) made by the powder metallurgy method was investigated by machining a piece of steel with a condenser-type discharge machine.
The results obtained are as follows;
(1) For Cu-70 wt% W with porosity up to 6.4 vol% made by the hot forging method, the erosion velocity increased and the erosion ratio decreased as the porosity, increased.
(2) For Cu-51 vol% W-2.8 vol% B-0.15 voloo TiB2 with porosity up to 6.8 vol% made by the infiltration method, the erosion velocity improved but the erosion ratio didn't as the porosity increased. This alloy containing B and TiB2 is superior to Cu-70 wt% W with the same porosity.
(3) For Cu-51 vol% W-2.8 vol% B-(0.15-1.2 vol%) TiB2 made by the infiltration method, the porosity increased and both the erosion velocity and erosion ratio improved with the TiB2 content.View full abstractDownload PDF (4710K) -
Yoshikazu Yamamichi, Yasuo Watanabe1974 Volume 21 Issue 7 Pages 200-204
Published: December 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFerric iron oxides made from pyritic ore differ from the conventional other ferric oxides in a content of the impurities, such as CuO, ZnO, SiO2, CaCO 3. Al2O3 and MnO, and in the firing condition of producing ferrite magnet. The purpose of the present paper is to show how the kind and/or the amount of these impu-rities effects on the firing condition. It was found that an addition of CuO, ZnO, or CaCO 3. accelerates the sintering rate, while an addition of MnO, SiO2 or Al2O3 retards that rate. (BH)max performance was not so much affected by the addition of CuO, ZnO or MnO, and it was reduced by the addition of the rest of additives.View full abstractDownload PDF (1963K) -
Masaaki Miyamoto, Testsuo Suzuki, Masumi Kindaichi, Yoji Mita1974 Volume 21 Issue 7 Pages 205-211
Published: December 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNegative resistance, conductive switching and memory effect are found in a-ferric oxide ceramics con-taining several kinds of oxide, ZnO, Bi2O3, CuO, etc. Same effects are also found in pure a-ferric oxide ceramics. It has been considered, therefore, that these effects are caused only by the nature of the system Fe-O, and these contained impurities play only subsidiary role such. as changing the equilibrium pressure of oxygen in the specimen.
Currents both in conductive state ("on-state") and in resistive state ("off-state") flow through the filamentary conductive path grown by electrical "forming". Current-voltage characteristics depend on the surrounding temperature and partial pressure of oxygen, but no electrode effect is found.
The mechanisms of electrical conduction have not been understood sufficiently, but the formation of filamentary conductive path has been found experimentaly. It seems that chemisorbed oxygen at the formed filament plays a great part to these characteristics of switching and memory effect. (Received August 8, 1974)View full abstractDownload PDF (4620K)
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