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Volume 11, Issue 1
Displaying 1-6 of 6 articles from this issue
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Akiyoshi Miyoshi, Yoshihiko Doi1964 Volume 11 Issue 1 Pages 3-13
Published: February 25, 1964
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn order to control the grain size of submicron grains in cemented tungsten carbides, (1) the relation between the morphorogical properties of W powders and the properties of WO3, and H2WO 4 3(NH 4)2O.12WO3.5H2O, and (2) the transition of particle sizes after the reaction W+C→WC, were studied by measuring the particle size with the permiability, the absorbtion, X-rays, apparent and tap density, and electron microscope. Several results were obtained as follow.
(1) The permiability, the apparent and tap density, and the colour of submicron W powders are subject to the size of aggregated particles.
(2) The size of the unit particles can determined better by using the X-ray, the absorbtion, the electron microscope methods.
(3) The size of the aggregates of fine W powders is subject to the size of WO3 particles, but the size of the unit particles is not subject to it.
(4) The particle size of WC powders is subject to the size of unit particles of W powders, either when the W powders are the weak aggregates that are easily broken into dispersed unit particles or when they are the strongly sintered aggregates of unit powders.
(5) The WC grain size of WC-Co alloy is subject to the size of WC powders, if grain growth does not occur during sintering.View full abstractDownload PDF (13099K) -
[in Japanese]1964 Volume 11 Issue 1 Pages 14-22
Published: February 25, 1964
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe influences of the kind of dispersed phase on the mechanical properties of dispersion stregthened copper alloys were discussed. The specimens were prepared by ball mill mixing of electrolytic copper powder (-325 mesh) with dispersed powder, followed by compacting, sintering, hot extruding and cold drawing, and annealed at 600°C for 1hr in vacuum before testing. Thoria, alumina and tungsten powders were used for the dispersion particle. For comparison, two kinds of pure copper were prepared, -one was of the sintered electrolytic copper powder compact and the other of the ingot of vacuum melted cathode copper. The experimental results showed that the strength of dispersion strengthened alloys could be determined by the interfacial energy between copper matrix and dispersed phase, the adhesion of the dispersed phase to the matrix, the degree of dispersion of particles in matrix, and the thermal stability of the dispersed phase. Copper-thoria alloy was the most excellent among the three dispersion strengthened alloys.
The grain size of the metal matrix of the dispersion strengthened alloy was progressively smaller with an increase in the amount of dispersed phase. In the case of pure metal or solid solution alloy, it has been shown in general that the smaller the grain size, the higher the strength was. For the dispersion strengthened alloy, the strength was affected much more by dispersion strengthening mechanism of dispersed particles themselves than by the grain size of the matrix.View full abstractDownload PDF (4189K) -
Tetsuo Shirayanagi, Yuji Nanya1964 Volume 11 Issue 1 Pages 23-28
Published: February 25, 1964
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn manufacturing metal powders by the electrolytic process, it is well known that properties of powders deposited depend on electrolytic conditions to be employed. In this paper, the properties of the copper powders which were electrodeposited from copper sulphate solution, were studied in relation to their electrolytic conditions. Copper powders were manufactured by various electrolytic conditions and were washed, dried and sieved through 80 mesh screen. On these powders thus prepared, particle size distribution, apparent density, specific surface and green density were measured. The particle shape was also observed by a microscope. The results obtained were as follows,
1) The properties such as apparent density, specific surface and particle size of powders were influenced remarkably by a concentration of copper sulphate in electrolyte.
2) The higher the temperature of the electrolyte, the particle size of powders became coaser and the density of green compacts became greater.
3) Change of the concentration of sulfuric acid had no remarkable effect on any properties measured, with an exception of a cathode efficiency.View full abstractDownload PDF (3086K) -
Toyoji Hirata1964 Volume 11 Issue 1 Pages 29-32
Published: February 25, 1964
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSExtensive researches in the past on methods of producing metallic powder by atomizing the molten metals with air or water jets have resulted in the industrialization of a number of these methods. However, no intensive research has yet been accomplished on the centrifugal method of atomizing the molten metals by revolving a rotor at an enormous speed, although the principle had been generally known. The research under discussion undertakes to probe the atomizing effects involved in the centrifugal atomizing process and thereby to bare the basic technicalities involved in the process. Many problems yet need to be solved before this process can be industrialized, but it has been confirmed that this process is highly promising for industrialization.
The principal dimensions of the rotor used in this experiment were as follows : outermost periphery of rotor 65mm, conical angle of inner surface 70°and maximum speed of rotor 20, 000 rpm. The nozzles on the underside of the melting pot were given five diameters of 0.8mm, 1.0mm, 1.2mm, 1.4mm and 1.6mm.
The predominant results obtained in the experiment are as follows :
(1) Distribution of the particle size is adjustable freely by changing the number of revolutions.
(2) The grain diameter of the metallic powder obtained is considerably uniform as compared with that prepared, by the method of utilizing gas ; that is, the distribution of particle size makes a sharp curve.
(3) Since no gaseous matter is employed in the atomizing process, the recovery of the obtained powder is very easily done.View full abstractDownload PDF (1573K) -
Tamotsu Fukatsu, Soukichi Takatsu1964 Volume 11 Issue 1 Pages 33-38
Published: February 25, 1964
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSFor the purpose of production of the sintered material having the properties of high-speed steel, the following two methods were investigated : 1) sintering the mixed powder of 1%C-18%W-4%Cr-12%Co.2) carburizing the sintered compact of the same composition excluding carbon.
In the case of method 1), adequate hardness was not obtained, because large carbide grains were formed during the sintering process and they were not dispersed in the subsequent heat-treatments. In the case of method 2), the microstructures of the carburized layer after quenching and tempering were the same with that of high-speed steel and the hardness of its portion was RC 65. In tempering, secondary hardening was apparently observed at 500-550°C and double tempering was more effective to increase the hardness. These phenomena are also closely similar to those of high-speed steel.
The effects of the treating factors were as follows : density of metal compact is important to obtain high hardness ; it shoud be higher than 94% of theoretical density at least. Therefore, the compacting pressure as high as possible is suitable and sintering at higher temperature and for longer time is desirable. Practically, optimum conditions were 10t/cm2, 1430°C and 3 hrs, respectively. For carburization, ordinary technique is applied and one example of the depth of crburized layer was about 1mm at 950°C and for 8hrs. Quenching from 1280°C was optimum for high hardness.View full abstractDownload PDF (5804K) -
[in Japanese]1964 Volume 11 Issue 1 Pages 39-43
Published: February 25, 1964
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (4015K)
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