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Volume 14, Issue 7
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[in Japanese]1967 Volume 14 Issue 7 Pages 283-291
Published: October 25, 1967
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (3118K) -
Toshitaka Fuziyama1967 Volume 14 Issue 7 Pages 292-301
Published: October 25, 1967
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe magnetic properties of sintered Alnico-8 type permanent magnet were studied.
The effects of boron addition, forming pressure, sintering time, the amout of binder, and the cooling time from 1250°C, the solution temperature, to 900°C were investigated. Results obtained were as follows :
1. Magnetic properties were improved by boron, and its optimum content was 0.01-0.02%, less than 0.06% in the Alnico-5 type magnet.
2. The forming pressure (2-8T/cm2) and the amount of binder (0-6%) had little effect on the magnetic properties, but at least 2 hours was necessary at 1250°C.
3. The binder was removed best in vacuum, but the removal in air must be done at the temperature as low as possible below 200°C.
In air, the same magnetic properties as those in vacuum were obtained when the binder was at vemoved at 100°C.
4. Rapid cooling from 1250°C to 900°C improved the mangtic properties, and the relation be-tween magnetic properties and the cooling time could be controlled by adding aluminum and silicon adequately.View full abstractDownload PDF (3304K) -
[in Japanese], [in Japanese], [in Japanese]1967 Volume 14 Issue 7 Pages 302-307
Published: October 25, 1967
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSince a preparation and catalytic activity of "Urushibara-Nickel" were published, some experimental efforts have been devoted by means of X-ray and electron diffraction techniques, but there is little publication indicating a unique relation between any physical or chemical properties of the Ni-fine particles and the catalytic activity, only similar behaviors to "Raney-Nickel" being reoorted.
The authors investigated the catalytic activity as a function of crystal (particle) size in the hydrogenation of acetone and various factors influencing the particle size in U-Ni-BA crystals, of which it has been reported that the catalytic activity of U-Ni-BA catalyst changes with the concentration of used Ni-chlorides.
As a result of the present experiment, it must be noted that ; (1) the cause of the cata-lytic activity can not be explained only by particle size, (2) in the U-Ni-BA crystals showing a remarkable activity, it was found from X-ray and electron diffraction analyses that "Hexagonal crystals" coexist in normal f.c.c. Ni-fine particles, and it was concluded also that the hexagonal crystals might be h.c.p. Ni included in f.c.c. Ni from the experimental result in which any possibility of existence of Ni-and Al-oxides, hydroxides and other substances was checked by the comparison of their X-ray patterns.View full abstractDownload PDF (2596K) -
Hisashi Suzuki, Takaharu Yamamoto, Nobuyoshi Chujo1967 Volume 14 Issue 7 Pages 308-313
Published: October 25, 1967
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSome properties of WC-10% (Ni-Fe) alloys sintered in vacuum at 1450°C for lhr were examined in relation to their carbon contents. Main results obtained are as follows ;
(1) The two-phase region was observed only in the alloys of which binder compositions were up to about 50% Fe in binder. Therefore, the properties of these alloys showed a regular change with the change of the carbon content in the alloys. (2) However, as the amount of Fe increased in those alloys, the contraction of the two-phase region, the shift of the region towards the higher carbon side and the decrease of the amount of dissolved W in binder phase of low carbon alloys were observed. (3) Following facts were also observed in the alloys having binder compositions of more than about 75% Fe in binder. i) mingling of b. c. c. binder phase with f. c. c. one, ii) fixed compositions of binder phase, regardless of the wide variation in the carbon content, iii) disappearance of the two phase region, iv) formation of M23C6 type compound. (4) Hardness of the alloys increased with increasing Fe content and reached a maximum at the binder composition of about 90% Fe in binder. Transverserupture strength decreased with a small amount of addition Fe and did not change mostly in the range of binder compositions from 10 to 75% Fe. Thus, it was shown that the alloy having binder composition of 75% Fe exhibited the most excellent mechanical properties. However, the strength was much inferior to that of WC-Co alloys. (5) Grain growth of WC was highly inhibited by increasing of Fe content.View full abstractDownload PDF (2021K)
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