巻号一覧
18 巻, 7 号
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清水 恵己, 深水 清1972 年 18 巻 7 号 p. 259-265
発行日: 1972/03/25
公開日: 2009/12/04
ジャーナル フリーThe variation of coercive force (iHc) with packing density in acicular and granular gamma ferric oxides, acicular and cubic cobalt doped gamma ferric oxides and hexagonal and granular barrium ferrite (BaO⋅6Fe2O3) was studied.
The iHc of these samples was measured at room temperature by a ballistic method in the low packing range (P=0.08-0.7g/cc/p).
The variation of their iHc with packing density depended on the morphological properties of their particles; In case of the acicular particles, the Me was remarkably or slightly decreased with increasing packing density. (b) the granular and cubic paticles, the iHc did not change with packing density. and (c) the hexagonal particles, the Me was increased with increasing packing density. In case of mixture of magnetic oxides and non magnetic oxides, the change of the iHc was the same as that of magnetic oxides only.
Hitherto, the variation of the iHc with packing density had been supposed to be affected by the interaction among particles and by the crushing of particles. In this paper, the variation of the Me with packing density was suggested to be due to the effect of the orientation of particles as well as the morphologic properties.抄録全体を表示PDF形式でダウンロード (4627K) -
焼結に及ぼすPbOの母塩の影響山口 修, 時任 保彦, 清水 澄1972 年 18 巻 7 号 p. 266-274
発行日: 1972/03/25
公開日: 2009/05/22
ジャーナル フリーThis paper deals with the effects of the mother salts of PbO, especially Pb2O(OH)2, on the sintering between PbO and PZT by means of X-ray diffraction, thermal dilatometry and electron microscopy. Results obtained are summarized as follows.
(1) The specimen containing PbO(massicot) produced by the decomposition of Pb20(OH)2 showed a remarkably good sintering, and the sintering rate was nearly independent on the sintering temperature in the presence of a liquid phase (PbO). This would be ascribed to the wettability and solubility between liquid (PbO) and solid (PZT) phase.
(2) The powder X-ray diffraction of PbO(massicot) thermally decomposed from Pb20(OH)2 gave a pattern which suggests a prefered orientation of powder particles in the direction of C axis.
(3) By the sintering of the non-stoichiometric PZT associated with the liquid phase(PbO), the shrinkage was proportional to n-th power of the time and the slope of the curve representing this relation was divided into three parts. These parts may correspond to the process of rearrangement of the particle grains, dissolution-recrystallization and grain growth. The value of n in the stage of dissolution-recrystallization was about one third and this coincided with the model by Kingery, that is, this stage would proceed by the diffusion controlled mechanism in the presence of the liquid phase. The activation energy for the initial sintering was in good agreement with that of the grain growth of PZT.
(4) The reaction rate for the formation of PZT was expressed by the equation of the Dander's type and the activation energy was about 96 kal/mol.
(5) The electro-mechanical coupling coefficient of the sintered bodies was about 50% and its dielectric constant was 350-400 at I KHz.抄録全体を表示PDF形式でダウンロード (4221K) -
徳永 洋一, 後藤 秀人1972 年 18 巻 7 号 p. 275-279
発行日: 1972/03/25
公開日: 2009/05/22
ジャーナル フリーNitrogen contents of iron powder compacts sintered in cracked ammonia were determined by direct chemical analysis. At the sintering temperature of 1200°C, maximum solubility of nitrogen in compacts seems to be reached at the earliest stage of sintering. Since the solubility of nitrogen in a-iron is considerably less than that in r-iron, the nitrogen content of sintered compact decreases drastically, during the relatively slow cooling from Ar3 down to 500°C after sintering. This desorption of nitrogen proceeds most rapidly at about 550°C for the low density compact, probably due to the catalytic effect of hydrogen on the inner surface of pore. In order to decrease the final content of nitrogen down to about 10 p.p.m. for the compact of 6.2 and 7.1 g/ee, the slow cooling rate below 100 and 2°C/min in the temperature range of 500-900°C are required respectively.抄録全体を表示PDF形式でダウンロード (410K) -
山崎 陽太郎, 佐藤 実1972 年 18 巻 7 号 p. 280-283
発行日: 1972/03/25
公開日: 2009/05/22
ジャーナル フリーA new method preparing pure and homogeneous fine oxide powders was developed, and its detail was discussed.
Inflammable solution of nitrate dissolved in ethanol was sprayed into the refractory tube with compressed air and then ignited leading to the oxide powders. The products oxide powders were introduced to the scrubber through the cooling pipe in order to separate the powders from gaseous bodies.
By this method, NiO and CoFe2O4 powders were obtained and their particle size, crystallite size and magnetic properties were investigated and the effects of nitrate concentration of mixed solution on their properties were discussed.
Results were obtained as follows.
1) The mixture of large sphere particles (0.5-2.0μ) and very fine crystallites (<200Å) were obtained. The ratio of large sphere particles to fine crystallits increased with the nitrate concentration of more than 0.014 mol/l.
2) The mean crystalline grain size calculated from line broadening of X-ray diffraction increased with the concentration of nitrate, from 430 Å at 0.0008 mol/l to 830 Å at 0.21 mol/l.
3) The coercive force of CoFe2O4 powders decreased rapidly with temperature, from 400 Oe at 30°C to 200 Oe at 100°C, and above 100°C the coericve force decreased monotonically. At room temperature the coercive force increased with decreasing grain size but above 100°C the relation was reversed.抄録全体を表示PDF形式でダウンロード (1135K)
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