巻号一覧
22 巻, 8 号
選択された号の論文の6件中1～6を表示しています
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森岡 恭昭1976 年 22 巻 8 号 p. 247-256
発行日: 1976/01/05
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (4566K) -
(三軸圧縮装置による成形条件の検討)島 進, 井上 隆雄, 大矢根 守哉, 沖本 邦郎1976 年 22 巻 8 号 p. 257-263
発行日: 1976/01/05
公開日: 2010/07/12
ジャーナル フリーThree dimensional compaction is carried out to determine a compaction criterion for metal powders. Compaction is attempted under various strain ratios or stress ratios. It is thereby confirmed that the compaction criterion is expressed by
F=√1/2{(σ1-σ2)2+(σ2-σ3)2+(σ3-σ1)2}+(σmlf)2,
where σ1, σ2 and σ3 are three principal stresses, f and F are functions of density ratio. In case of copper powders tested
f=1/2√1-γ and F=46.7γ2.5⋅
The compaction criterion appears to be a plastic potential which leads to a stress-strain relationship expressed by
dεi=dλ{σi-(1-2/9f2)σm} (i=1, 2, 3).
The above equations are utilized to calculate a pressure versus density ratio in closed-die compaction, which shows a good agreement with the experimental results.抄録全体を表示PDF形式でダウンロード (1741K) -
島村 慶三, 鈴木 一雄1976 年 22 巻 8 号 p. 265-270
発行日: 1976/01/05
公開日: 2009/05/22
ジャーナル フリーTo clarify the pore elimination processes in sintered preforms under static compressive stress, a model experiment is carried out.
Spherical copper particles with particle size between 10 and 12 mesh are sintered in a graphite mold at 1000°C for 1 hr. Sintered preforms with a relative density of 48% are then compressed in cylindrical dies at compacting pressures from 0.5 to 10 ton/cm2 without any lubricant. Preform density after deformation is measured by means of size-weight measuring method and Archimedean method, and plotted against compacting pressure. Pore elimination due to deformation is examined by a scanning electron microscope.
The results obtained are summarized as follows:
1) Deforming process is separated into three characteristic stages. The transition from stage 1 to stage 2 occurs at the preform density of 74% theoretical, and the transition from stage 2 to stage 3 corresponds to the change from continuous to closed pore.
2) Plastic deformation occurs in all the three stages, in stage 1 transitional restacking takes place, in stage 2 local deformation at contacting regions and stage 3 overall deformation of the bulk material.
3) The volume of surface residual pore is about two-thirds of total pore volume.抄録全体を表示PDF形式でダウンロード (5245K) -
黒木 英憲, 白川 充祉, 徳永 洋一1976 年 22 巻 8 号 p. 271-278
発行日: 1976/01/05
公開日: 2009/05/22
ジャーナル フリーIt has been reported by H. Kuroki, T. Wakabayashi and Y. Tokunaga (Journal of the JSPM, 17 (1971), 307, in Japanese) that most of the commercial iron powders show an.abnormal coarsening of ferritic grains in the density range of 6.8-7.3 g/cm3. In the present work, some attempts were made to clarify the cause of this coarsening.
Compacts, 8×8×20mm, were prepared from carbonyl iron powder (gaf'L') following the procedure of pressing under 4 t/cm2, presintering at 800°C for 30min, re-pressing under 3-11 t/cm2 and sintering at 850-1200°C for 5 min-48 hr in dry hydrogen.
Results were summarized as follows:
The coarse grains were formed during the Ar3 transformation and had a tendency of growing in a columnar structure with the axis along the direction of the heat flow.
This structure was observed not only in sintered iron but also in cast iron of high purity, and the structure was promoted by a very small content of oxygen, but suppressed by that of carbon.
In low density compacts, this type of coarsening was controlled by the sticking of grain boundaries to pores.
In high density compacts, fine grains were formed in some cases, as the result of deoxidation and/or carburization caused by the lubricating oil enclosed in pores under high re-pressing pressure.抄録全体を表示PDF形式でダウンロード (9004K) -
横田 勝, 後藤 隆茂, 三谷 裕康1976 年 22 巻 8 号 p. 279-285
発行日: 1976/01/05
公開日: 2009/05/22
ジャーナル フリーThe oil impregnated tin bronze sintered bearing is one of the most popular industrial material in the sintered mechanical parts. A number of investigators have been studying about the conditions suitable for the bearing performance of this material. However, factors affecting the bearing performance are so many and complex that those systematic relations have not been clarified completely. Therefore, we picked up the oil supply efficiency of oil supply as one of the factors and discussed it's relation to the bearing performance, by using the two kinds of oil impregnated tin bronze sintered bearings; one is made from the pre-alloyed powders. In this case we assumed the efficiency of oil supply is closely related to the permeability.
Results. obtained were as follows:
1) Despite of coincidence of the composition and the intercommunicating porosity of the bearings, the per-meability of the bearing made from the pre-alloyed powders is higher than that made from the mixed powders, where all the powders used in this experiment were obtained as commercial ones and these particle sizes were all minus 100 mesh.
2) Under the condition of low speed operation, the bearing performance of the bearing made from the pre-alloyed powders was superior to that made from the mixed powders. On the other hand, under the condition of high speed operation those differences were not measured.
3) The hardness of matrix affects the bearing performance, e.g. the harder the matrix, the lower the frictional coefficient and the temperature increment of bearings in general where the hardness of matrix was varied by the tin content of the bearing.
5) Radial crushing strength of the bearings made from the prealloyed powder was about twice as high as those made from the mixed powders.抄録全体を表示PDF形式でダウンロード (1892K) -
上原 保彦1976 年 22 巻 8 号 p. 286-292
発行日: 1976/01/05
公開日: 2009/12/04
ジャーナル フリーEffect of mechanical treatment on the polymorphic transformation in copper ferrite was investigated by X-ray diffraction analysis. The results obtained are as follows: 1) The transformation from cubic to tetragonal structure at temperatures between 320°C and 360°C was promoted by the mechanical treatment such as pressing or milling. The transformation isotherms were represented by Dander's equation, and the activation energy of the transformation was about 45k cal/mol, which was independent of the mechanical treatment and agreed with that of the oxidation. 2) For long-time milled or ground samples, the trans-formation from cubic to tetragonal structure did not occur below about 500°C. However, after being annealed higher temperatures the transformation occurred. 3) The tetragonal structure transformed into the cubic one at room temperature by long-time milling or grinding. It is considered that the cooperative Jahn-Teller ordering was destroyed by lattice imperfections, such as dislocations and stacking fault generated by milling or grinding. 4) The residual tetragonal structure which had not been transformed was transformed into the cubic one by heating above about 360°C.抄録全体を表示PDF形式でダウンロード (1889K)
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