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Volume 7 (1960)
- Issue 6 Pages 255-
- Issue 5 Pages 197-
- Issue 4 Pages 149-
- Issue 3 Pages 99-
- Issue 2 Pages 35-
- Issue 1 Pages 1-
Volume 7, Issue 6
Displaying 1-3 of 3 articles from this issue
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Toshihiko Tsunowo, Mitsuo Chubachi, Toshitaka Fujiyama1960 Volume 7 Issue 6 Pages 255-268
Published: December 25, 1960
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSStudies were made, in 'order to improve the magnetic property of the sintered NKS permanent-magnets by using vacuum sintering technique, of the effect produced on it by addition of the above mentioned agents, to find their magnetic property, sintered density, hardness, dimentional changes, and microstructure. The addition of the above mentioned elements improves the quality of the sintered NKS permanent-magnets remarkably. The addition of boron or phosphorus causes grain growth in the structure of the magnets, and an eutectic structure appears in the grain boundary when the boron or phosphorus is added to excess in quantity. This grain growth scarcely appears in the structure by the addition of titanium but does appear when zirconium is added.
The yield of aluminum is 90-95% when 8-15%(wt) of aluminum is added, and increases straightly with the quantity of aluminum. Accordingly the loss of aluminum is 10-15% (wt). The lost of aluminum has mostly changed into aluminum-oxide by sintering process in low vacuum and remains as such in the magnets, but vaporizes by sintering process in high vacuum.View full abstractDownload PDF (14300K) -
[in Japanese], [in Japanese], [in Japanese]1960 Volume 7 Issue 6 Pages 269-274
Published: December 25, 1960
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSUO2 powders were prepared from uranium oxalate and ammonium diuranate by reduction with hydrogen at various temperatures ranging from 600°C to 1300°C. Their morphological properties were determined by optical microscope, electron microscope, and X-ray diffraction techniques.
Observation by electron microscope showed that the UO2 particles prepared, in all cases, consisted of the small unit particles which were linked with each other resulting formation of aggregates. The size determinations of unit particle were undertaken by carrying out direct measurement on the electron microphotographs and also by the X-ray method by means of line broadening of Debye-Scherrer ring. Results obtained show fairly good agreement, and the size of unit particles increased with increasing temperature of reduction. The aggregates of UO2 particles, we obtained, resembled in shape with original crystals of their mother salts and, thus, the shape of aggregates prepared from oxalate was square plate like and from ammonium diuranate which was obtained by homogeneous precipitation method with urea, was irregulare plate like. The size of these aggregates decreased with increasing temperature of reduction.
The crystal of ammonium diuranate obtained by heterogeneous precipitation method with ammonia, was so fine crystal, that we could not observe the shape of mother salt maintained on the aggregate of UO2 prepared from this salt.View full abstractDownload PDF (6853K) -
Susumu Okuda, Keikichi Inoue, Isao Uei1960 Volume 7 Issue 6 Pages 275-279
Published: December 25, 1960
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe heat of immersion method devised by Harkins-Jura in 1944 has such a significant disadvantage that the method is accompanied by an unavoidable error with the powders that have capillary condensation in adsorption of vapor of the liquid in which the powders are immersed. Previously, the authors have been presented an approvable means to develope the applicability of the heat of immersion method to many kinds of powders not as a standard method but as a common use independently of the capillary condensation phenomenon.
On the basis of the foregoing results, the surface areas of several kinds of oxide powders together with clay minerals were determined and the obtained results were compared with those from the other methods, briefly the B. E. T. method. Simultaneously, the effect of pretreatment of the powder samples on their surface area values was investigated.
The obtained conclusions are digested as follows :
(1) The heats of immersion in water for the powder samples which are equilibrated at an unsaturated water vapor pressure near before capillary effect provide surface area values that are in considerable agreement with those from the B. E. T. method using nitrogen as adsorbate.
(2) Though of course precise data could not be expected, the heat of immersion method may be capable of being extended to many kinds of powders as routine work regardless of the capillary condensation.
(3) The surface area values of silica gel, anatase and kaolinite are affected considerably by the condition of pretreatment (degasing temperature).View full abstractDownload PDF (299K)
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