巻号一覧
13 巻, 1 号
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安藤 徳夫1966 年 13 巻 1 号 p. 1-12
発行日: 1966/02/25
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (7492K) -
藤山 俊尚, 榎木 喜一1966 年 13 巻 1 号 p. 13-21
発行日: 1966/02/25
公開日: 2009/05/22
ジャーナル フリーTo establish the design of sintered iron yoke used for speaker, various factors of dimension, shape, surface treating, history of iron powder raw materials, and gap between the yoke and permanent magnet core were studied.
The aging properties of B5, B25, B100and the temperature variation of μm, Hc, and B25 were also studied.
NKS-7, NKS-5 type Alnico magnet were used for permanent magnet cores.
All the yokes except for ring specimens were prepared by cutting from sintered iron of 25φ×20mm block.
Specimens used for surface treating test were heated in an atmosphere of steam. Specimens for B5, B25, B100, Bg and φT are of ring and pot type.
These specimens were formed by the pressure of 6t/cm2 and sintered in the atmosphere of cracked ammonia gas for 3hr at 1100°C.
The yoke of high density contains about 1.0% (wt) of phosphor. Gap flux density (Bg) of pot type yokes are correlated to the dimension of side and of the thickness of bottom ; it sharply decreases at a certain dimension.
The yoke with hole in the bottom has also similar properties.
Yokes heated in the steam has no variation in Bg and φT.
Bg or φT values were not so much affected by the history of iron powder raw materials and their absolute values were slightly lower than those of carbon-steel (S10C).
Temperature dependence of μm, Hc and B25 were quite similar with those of S10C and exhibits no aging in flux density B25, B100抄録全体を表示PDF形式でダウンロード (495K) -
富沢 利, 上田 卓弥, 徳下 元之, 末広 建介, 中川 龍一1966 年 13 巻 1 号 p. 22-27
発行日: 1966/02/25
公開日: 2009/12/04
ジャーナル フリーThis paper deals with the iron powder for powder metallurgy. This iron powder was produced from pyrite by a new process, which consists of flotation, roasting, treatment with nitric acid, reducing by hydrogen, rolling and annealing. Authors examined the characteristics of the iron powder. The results obtained are summerized as follows.
1) The iron powder was very pure.
2) The apparent density and flow rate of the iron powder could be improved by successive treatments of rolling and annealing.
3) The apparent density of the iron powder could be controlled from 2.4g/cm3 to 3.3g/cm3 by conditions of rolling and annealing.
4) In the case of the iron powder of which the apparent density was 2.4g/cm3, compressibility was compatible to the imported iron powder, but sinterability was greater than that of the imported iron powder. As for the mechanical properties, the iron powder was better than the imported iron powder.抄録全体を表示PDF形式でダウンロード (1370K) -
今岡 保郎1966 年 13 巻 1 号 p. 28-36
発行日: 1966/02/25
公開日: 2009/12/04
ジャーナル フリーDuring slow oxidation of magnetite powder in the air, we can obtain Fe3O4-γ⋅Fe2O3 solid solutions. There are expressed in the formula ?? x/3Fe3-x/3O4, where ?? is the cation vacancy and (x) is the degree of oxidation. The composition which corresponds to (x)=0.65 shows an abnormal increase in coercive force. After the sample is prepared, its coercive force increases gradually ; this phenomenon is a kind of aging effect.
The present author tries to describe this abnormal phenomenon of magnetic properties and discuss the origin and mechanism of the effects. The author applies the "nucleation model" to the aging effect. The oxidation does not proceed uniformly in the magnetite particle and some structural defects act as the nuclei of oxidation. These nuclei behave supermagnetically when their sizes are small, but, when they grow up to the range of single domain size, their coercive force increases. The aging effect takes place by the diffusion of ferric ions, cation vacancies and electrons. The activation energy for ion diffusion decreases because this solid solution is an electron conductive substtance. Further experiments and discussions will be published.抄録全体を表示PDF形式でダウンロード (663K)
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