巻号一覧
24 巻, 1 号
選択された号の論文の5件中1～5を表示しています
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中西 典彦, 高野 幹夫, 組藤 浩志1977 年 24 巻 1 号 p. 1-5
発行日: 1977/01/05
公開日: 2009/12/04
ジャーナル フリーFine powders of MgO were produced from aqueous solutions of magnesium sulfate by means of "Freeze-Drying Processing" (F.D.P.). In order to determine the thermal decomposition temperature of the sulfates obtained by F.D.P. and the amount of water involved in the F.D.P. powders, and to identify the structure of the finally formed oxides, thermal gravimetry, differencial thermal analysis and X-ray diffraction methods were carried out. The observation of shapes and particle sizes of sulfate and oxide powders was also made by transmission electron microscopy. Mössbauer spectroscopy was applied to investigate the behaviour of water molecules (dehydration) in the process of freeze-drying of the sulfate solutions including ferrous (Fe2+) ions. The particle shape was thin plate like and its breadth of 0.1-0.2 μ, and the thickness was decreased with decreasing concentration of the initial solution. As a result, the followings were confirmed: (1) The solution including ferrous ions is not so easily dehydrated as that without ferrous ions. (2) Fine powders of MgFe2O4 can be produced as a result of the oxidation of ferrous ions in the process of freeze-drying.抄録全体を表示PDF形式でダウンロード (1559K) -
武川 淳二郎, 増田 良道1977 年 24 巻 1 号 p. 6-11
発行日: 1977/01/05
公開日: 2009/05/22
ジャーナル フリーIn order to determine the yield criteria for metal powder undergoing compaction and to ascertain the effect of shear stress on the densification, triaxal compression tests were made on iron, copper and aluminium powders under hydrostatic confining pressure up to 600 MPa. The yield criteria for these powders changed gradually from a Mohr-Coulomb type at low hydrostatic confining pressure under 200 MPa to a Tresca type with increasing the confining pressure. The angles of internal friction measured on iron, copper and aluminium powders at low confining pressure were 14.7°, 13°and 9.7°respectively. During triaxial compacting, these powders were densified abruptly at the outset of yielding and successively densified through three stages, and the mean normal stress required to obtaining the compact of a given density was 50-65% lower than that in the isostatic compaction. The structure of produced compact showed a remarkable plastic deformation of particles in the shearing direction.抄録全体を表示PDF形式でダウンロード (4415K) -
関藤 裕司, 久野 洋1977 年 24 巻 1 号 p. 12-16
発行日: 1977/01/05
公開日: 2009/12/04
ジャーナル フリーChanges in the pore structure were searched by the measurement pore size distribution and cumulative pore volume, on cinnamic acid and adipic acid compacts hot-pressed at various temperatures and pressures. Studies are mainly on the initial and intermediate stages of the densification during which plastic flow mechanism predominates. When hot-pressed under the constant pressure, the total pore volume decreased rapidly with increasing temperature, particularly near the melting point, and pores shrank uniformly with keeping their similar shape. On the other hand, when hot-pressed under the constant temperature, pore volume decreased with increasing pressure but the degree of volume decrease became less when the pressure was high. Furthermore the larger pores shrank rapidly than the smaller ones in contrast to the former case.抄録全体を表示PDF形式でダウンロード (315K) -
Osamu Yamaguchi, Akiyasu Kaji, Kiyoshi Takeoka, Kiyoshi Shimizu1977 年 24 巻 1 号 p. 17-23
発行日: 1977/01/05
公開日: 2009/05/22
ジャーナル フリーThe sintered density, and the initial sintering and grain growth kinetics of spine (MgAl2O4) derived from alkoxide were investigated by means of dilatometry, X-ray diffraction, electron microscopy and the measurement of isothermal shrinkage. The obtained results are summarized as follows:
(1) Spinet powders calcined between 600 and 1000°C consisted of aggregates of small particles, and particle growth was observed at 1200°C.
(2) The crystallite size of spinel increased markedly at temperatures above 1200°C.
(3) The highest sintered density was obtained for the powder calcined at 800°C for 2 h. Under these calcining conditions, the spinel compact exceeding 95% of theoretical density was obtained by sintering at 1600°C for 4 h in air.
(4) The initial sintering kinetics of spinet was determined from 1100 to 1300°C. The sintering process was governed by the volume diffusion of oxygen ions which was represented by D=22.9 exp (-119, 000/RT) cm2/sec.
(5) The grain growth of spinel was represented by the expression of G2-G02=kt, and the temperature dependence of k was given by k=12.7 exp (-116, 000/RT) cm2/sec.抄録全体を表示PDF形式でダウンロード (2604K) -
渡辺 三千雄, 粟野 洋司, 団野 敦, 木村 尚1977 年 24 巻 1 号 p. 24-28
発行日: 1977/01/05
公開日: 2009/05/22
ジャーナル フリーDeformation and densification behavior of porous preforms in hot trapped die upsetting and closed die forging (double-cup and doulle-boss) was investigated with Fe-0.5C powder preforms.
For forging processes so far studied including those described in the previous report, no marked difference in deformation behavior was observed between powder preforms and bar stock materials, except cracking tendency of the former. Below 8t/cm2 of forging pressure, the mean density of sinterforged specimens increased with increasing material flow during deformation, depending upon the deformation type, but above 8t/cm2 the density more than 99.5% of the theoretical value was obtained for any type of forging processes except upsetting. In closed die forging, densification in the specimens proceeded from the zone in initial contact with the punch, through high shear stress zone and then to the free surfaces with some delay.
Residual pore defects were obtained on cracked surfaces, die chilled areas and insufficiently deformed surface layers. Re-sealing of in-process cracks was suggested to occur under suitable forging conditions.抄録全体を表示PDF形式でダウンロード (1882K)
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