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Volume 30, Issue 5
Displaying 1-7 of 7 articles from this issue
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Mikio Kishimoto, Susumu Kitaoka, Masahiro Amemiya1983 Volume 30 Issue 5 Pages 173-177
Published: July 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTo examine the kind and the origin of magnetic anisotropy in γ-Fe2O3 particles, cobalt-epitaxial iron oxides and cobalt-doped iron oxides, the temperature variation of coercivity and magnetic torque was measured for the magnetic sheets prepared by using the oxide particles. The magnetic anisotropy of y-Fe2O3 particles was a uniaxial anisotropy due to the shape anisotropy. The main magnetic anisotropy of cobalt-epitaxial iron oxides was also uniaxial anisotropy, which was expected to be induced in cobalt-ferrite when the cobalt-ferrite was crystallized on the surface of γ-Fe2O3 particles. The coercivity of cobalt-doped iron oxides was nearly based on the crystalline magnetic anisotropy. The crystalline magnetic anisotropy energy showed a remarkable variation for temperature, compared with the uniaxial anisotropy energies of γ-Fe2O3 particles and cobalt-epitaxial iron oxides.View full abstractDownload PDF (297K) -
Kenji Suzuki, Mitsuo Akabori, Koreyuki Shiba1983 Volume 30 Issue 5 Pages 178-183
Published: July 25, 1983
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe polished hemispheres of ThO2 kernels were irradiated by fission fragments, which recoiled from the covered Al-U alloy foils. After irradiation, the lattice parameters of the kernels were measured by micro-beam X-ray diffractometer. It was found that the lattice parameter increased with increasing fission fragment dose and reached a saturation value at doses higher than about 5×1016 fission fragments-cm-3. With increasing grain sizes from 4.0 to 19.3 μm, the saturation values of lattice parameter changes increased from approximately 0.07 to 0.18%. The recovery began at about 400°C in all specimens and the temperature of the complete recovery had a tendency to become higher with increasing grain size. These results lead to a conclusion that the grain boundaries act as a sink of the defects created by fission fragments.View full abstractDownload PDF (486K) -
Kazuhiko Majima, Naoyuki Ishigaki, Shuichi Miyaoka1983 Volume 30 Issue 5 Pages 184-189
Published: July 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSUsing three different kinds of Sm(Co, Fe, Cu)7 powder compacts whose particle diameters were 2.3, 4.1 and 6.0 μm, the effect of particle size on the sintering characteristics and the magnetic properties was investigated mainly by means of dilatometric method and EPMA.
The results obtained are as follows:
(1) The sinterd density of the Sm(Co, Fe, Cu)7 powder compacts increased with decreasing diameter of powder, and the maximum value was obtained at 2.3 μm in any sitering temperature from 1180°C to 1240°C, while the maximum energy product (BH)max was maximum at 4.1 μm.
(2) In the higher sintering temperature range than 1240°C, the liquid phase sintering was observed in all specimens above mentioned, where the amount of liquid increased with increasing diameter of particle.
(3) The oxygen concentrations of the sintered Sm(Co, Fe, Cu)7 compacts were determined to be 900 ppm, for 6.0 μm, 1200 ppm for 4.1 μm and 2800 ppm for 2.3 μm specimen. These high values of oxygen concentration are due to the strong affinity of samarium for oxygen, and the above mentioned results have been confirmed to be deeply connected with compositional shift of Sm(Co, Fe, Cu)7 alloy by oxidation.View full abstractDownload PDF (4818K) -
Shiro Kohara, Kiyohiko Tatsuzawa1983 Volume 30 Issue 5 Pages 190-195
Published: July 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSSintering behavior of Fe-Cu compacts prepared with plated powder was studied by means of dilatometer and electron probe micro analyser. The copper growth phenomenon was markedly decreased during sintering the compacts of plated powder, compared with the case of mixed powder. The decreased copper growth in the compacts of plated powder can be attributed to the following reasons: (1) accelerated sintering in solid state in the temperature ranges of alpha and also gamma of iron, (2) contraction by the rearrangement of iron particles at the melting point of copper, and (3) suppression of expansion due to decreased pene-tration of liquid copper between iron particles, and also diminished grain boundary diffusion of copper and decreased liberation of hydrogen gas accompanied with the Cu penetration above the melting point of copper.View full abstractDownload PDF (2955K) -
Aspects of Start-up and Behavior of Solid LubricantsTohru Kohno, Yoshio Nishino1983 Volume 30 Issue 5 Pages 196-200
Published: July 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTo elucidate the aspects of lubrication of oil impregnated sintered bearings which are set in real high speed revolution machinery and tools, the sintered bearings which compositions are Cu-9%Sn and Cu-9%-Sn-1% C were tested using the high and low viscosity lubricant oils.
The results obtained are as follows:
1) When oil impregnated sintered bearings were set into real high speed revolution machinery and tools, it was found that they are driven under an extremely severe boundary condition, because no sufficient time can be given for the geometrical conformity of the bearings, as the number of revolution of the shafts reaches the fixed high speed one just after the starting. Consequently, large amounts of wear of the bearings occurred at this stage and it was supposed that the bearings may seize in the worst case.
2) The coefficient of friction of the start-up was affected extremely by the viscosity of the lubricant oil. Consequently, the values of the coefficient of friction did not indicate the degree of the severity of the state of lubrication.
3) Adding solid lubricants alleviated the severe state of boundary lubrication of the start-up. It was considered, however, that solid lubricants added by the conventional way into the bearing matrix increase the apparent viscosity of the oil and consequently increase the coefficient of friction and the bearing temperature after transferring to the hydrodynamic conditions at the regular state.View full abstractDownload PDF (1796K) -
Sachio Oki, Toshihiko Akiyama, Keiichiro Shoji1983 Volume 30 Issue 5 Pages 201-206
Published: July 25, 1983
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTransformation fearutes of sintered Cr-Mo steel (Fe-1 %Cr-0.2%Mo-0.35%C) containing frro-molyb-denum powder as an alloying additive were studied, and compared with those of which made from metallic molybdenum powder or molybdenum carbide powder. Distribution of molybdenum in each specimen was also examined quantitatively by EPMA.
The microstructures of molybdenum segregated area of the specimen containing ferro-molybdenum were similar to those of the specimen containing metallic molybdenum. On the other hand, the region of bainite formation in the CCT diagram was extended to longer cooling time, and similar to that of the specimen containing molybdenum carbide.
These results were discussed from the aspect of the relationship between the heterogeneity of molybdenum and the microstructures.View full abstractDownload PDF (3265K) -
Masahiro Yoshimura, Shin-ya Kikugawa, Shigeyuki Somiya1983 Volume 30 Issue 5 Pages 207-210
Published: July 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFine powders of a-Al2O3 were prepared by hydrothermal oxidation of Al metal powders. Under 100 MPa, Al yielded Boehmite between 200°C and 400°C, and finally produced a-A1203 above 600°C in the open capsule. On the other hand, unreacted Al metal remained until 700°C in the sealed capsule. This hydrothermal oxidation method is one of the methods to prepare fine a-Al2O3 particle having around I Inn in size.View full abstractDownload PDF (1851K)
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