All issues
Volume 29, Issue 5
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Koji Hayashi, Naomi Namiki, Yoshio Takashima, Hisashi Suzuki1982 Volume 29 Issue 5 Pages 159-163
Published: July 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe WC-β-Co alloys with different compositions were in vacuum sintered, and subsequently heated mainly in N2 at 1473-1723 K for 1.8-43.2 ks to form a hard phase layer on the specimen surface. The formation of hard phase layer was suggested by the authors' previous results.
It was found that the hard phase layer showed a smooth outersurface, when the alloy was heated in a solid state; The layer grew from the surface to the inside; The thickness of layer increased with heating temperature and time, N2 pressure, f and Co contents; The relation, xoc√t, was held, where x and t are the thickness and heating time, respectively.View full abstractDownload PDF (3180K) -
Tadatoshi Honda1982 Volume 29 Issue 5 Pages 164-169
Published: July 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis work was made to clarify the influences of grinding, annealing after grinding and buff-finishing on fatigue strengths of electrolytic and carbonyl iron powder compacts sintered at 1123 and 1423 K for 3.6 ks.
The results obtained were as follows:
(1) The plastic flow induced by the grinding occurred on the surface layers of sintered iron compacts toward the grinding direction and the worked surface layers were formed in the region about 10μm thickness under the surfaces of them. The pores near the surface of specimens were collapsed to the grinding direction and became a linear-like microcrack.
(2) From X-ray residual stress measurement, the residual stress in the surface layer of as-sintered specimen was slight, but that of as-ground specimen induced a very higher tensile and compressive stress, respectively, in parallel and transverse to the length of specimens. In the other specimens, the tensile residual stress disappeared and varied to compressive side.
(3) In all fatigue strengths of specimens prepared by various processes, that of annealed specimen after grinding was the largest. This was caused by the reduction of the residual stress, the formation of some surface layers without pores and the nucleation of a few fine grain due to the recrystallization during annealing process.View full abstractDownload PDF (3552K) -
Kiichi Oda, Tetsuo Yoshio, Koichi Hirata, Kazuo O-oka, Katsuaki Takaha ...1982 Volume 29 Issue 5 Pages 170-175
Published: July 25, 1982
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSCrystalline barium ferrites with compositions of BaFe2O4 and BaFe12O19 were prepared through the amorphous state by calcining gels which were obtained by the hydrolysis of metal alkoxide mixture. The crystal formation process differs significantly from that of conventional solid state reaction; the formation temperature is fairly low and the process does not involve the intermediate crystal phase.
Amorphous barium ferrite crystallized into a monoferrite at 500°C and a hexaferrite at 600°C. Particle size of the hexaferrite prepared under the heat-treatment condition at 700°-1000°C for 2 hr was ranged from 0.15 μm to 0.4μm corresponding to the magneticolly single-domain particle. The relationship between coercive force and particle size in the present work showed good connection with that of the multi-domain region.
Based on these results, their amorphous nature was also discussed.View full abstractDownload PDF (1643K) -
Hiroshi Utsugi, Atsushi Endo, Noboru Suzuki, Nobuko Hanaoka, Kan Oshio ...1982 Volume 29 Issue 5 Pages 176-181
Published: July 25, 1982
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe pyrolysis and pyrolysis products of basic magnesium carbonate were investigated by means of the infrared spectra, X-ray diffraction pattern, adsorption of argon at 77°K, scanning electron microscope (SEM) and the catalytic activity on the pyrolysis of isopropanol. The followings were found; (1) The formation of H2O from OH- and CO2 from CO32-proceeds separately in pyrolysis of basic Mg carbonate and the former proceeds at lower temperature. (2) The dehydrated sample including the partly decomposed products of carbonate showed to be amorphous in X-ray diffraction pattern. (3) The sample after pyrolysis at 450°C in which the pyrolysis of basic Mg carbonate performed showed the highest surface area such as 460 m2/g and the presence of MgO crystallite was recognized by X-ray diffractometry. (4) The samples after pyrolysis at higher temperature were identified to be MgO by X-ray diffractometry whereas the SEM photographs of these samples were observed to be the same shape as that of the original basic Mg carbonate. (5) The absorption band due to CO32-at 1450 cm-1 splits into two at 1410 cm-1 and 1510 cm-1 because of the degenerate symmetric streching vibration of CO32-due to perturbation with OH-in infrared spectra of basic Mg carbonate nevertheless these bands showed the degenerate with each other due to recovery of symmetry of CO32- accompanying with the dehydration of original basic carbonate. (6) The followings were produced by pyrolysis of basic Mg carbonate in various temperature range; 4MgCO3⋅Mg(OH)2⋅4H2O after heating at 30-150°C, mixture of 4MgCO3⋅Mg(OH)2⋅4H2O and MgO⋅MgCO3 after heating at 200-350°C, mixture of MgC⋅MgCO3 after heating at 350-450°C and MgO after heating at above 450°C. (7) MgO produced by the pyrolysis of basic Mg carbonate proceeds selectively the dehydrogenation in pyrolysis of isopropanol. It was remarkable that the smaller crystallite of MgO showed the high catalytic activity in the pyrolysis of isopropanol.View full abstractDownload PDF (1449K) -
Norihiko Nakanishi, Mikio Takano, Akio Chyo, Kazuhiro Kimura, Hiroshi ...1982 Volume 29 Issue 5 Pages 182-186
Published: July 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe report in the article a new process of preparing Cu-Al2O3 fine powder of good quality for 0.3 and 0.6 wt%Al2O3 dispersion strengthened alloys. In this process freeze-dry techniques are applied to the starting material of Cu- and Al-nitrates.
Detailed processes are as follows: (1) Mixture of two molten salts of Cu- and Al-nitrates were atomized into liquid nitrogen bath and instantaneously freezed, (2) for dehydration kept under vacuum condition for 1 day at -70°C and kept for 1-3 day at room temperature, (3) then held for 2-5 day at 95°C where the crystal structure of (Cu, Al) nitrate changed into that of basic nitrates, (4) fired for 1 hr at 260°C in which the basic nitrates were decomposed into oxides, and (5) reduced by hydrogen gas for 2 hrs at 400°C. The powders thus obtained were treated with cold-pressing and then hot-isostatic pressing.
Particle shape of powder in each step and particle size distribution of oxide after HIP treatment were observed using scanning electron microscope and optical microscope, respectively.
Hardness, density and electro-conductivity of the after-HIP-treatment-samples were also measured, which were essential character for spot-welding electrode.View full abstractDownload PDF (1578K) -
Kenji Suzuki, Mitsuo Akabori, Koreyuki Shiba1982 Volume 29 Issue 5 Pages 187-190
Published: July 25, 1982
Released on J-STAGE: December 04, 2009
JOURNAL OPEN 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 microbeam X-ray diffractometer. It was found that the lattice parameter increased initially in a linear relationship with increasing fission fragment dose and reached a saturation value at doses higher than about 1×1016 fission fragments⋅cm-3. The saturation value was smaller for the fine-grained specimen than for the coarsegrained. The recovery began at about 400°C for both the specimens and lasted to higher temperature for the coarse-grained.View full abstractDownload PDF (3371K)
- |<
- <
- 1
- >
- >|