巻号一覧
24 巻, 4 号
選択された号の論文の5件中1～5を表示しています
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石橋 渡1977 年 24 巻 4 号 p. 107-112
発行日: 1977/06/05
公開日: 2009/05/22
ジャーナル フリーAs an application of electrode erosion by electric discharge, a new method was developed in which fine powder was produced by the spark discharge.
When metal pellets are dipped into the liquid medium, the contact points of each pellets form the spark points. The pellets repel momentarilly each other by the impulse of spark discharge, and maintain its steady spark discharge by shifting the contact points and inhibiting the conversion to arc discharge. Thus fine powder is produced at spark points.
In spark discharge circuit, electrostatic capacity of condenser is set as small as possible, and enhances the condenser energy by higher charge voltage. In addition, the discharge voltage is brought to be higher by quenched spark gap.
The powder quantity is increased with the higher discharge voltage (10-40 kV) and its particle size becomes smaller with increase of frequency (230-610 kHz). Discharge condition has been investigated for producing fine powder (0.05-5μm) from aluminum, copper and iron materials. Finally the theoretical description has been given with regard to the mechanism of producing the fine powder at spark points.抄録全体を表示PDF形式でダウンロード (3220K) -
石橋 渡1977 年 24 巻 4 号 p. 113-117
発行日: 1977/06/05
公開日: 2009/05/22
ジャーナル フリーWhen a spark discharge takes place at the contact points of pellets (metal, alloy or graphite) dipped in the liquid medium (pure water or oil), the powder produced from the pellets reacts with the medium at the spark points.
This paper describes stoichiometrically the reaction between the powder and the liquid medium at the spark points by means of mass balance being based on the quantity of the cracked medium, the quantity of gas and powder produced, composition of gas, and the property of powder.
The results are summarized as follows:
1) WC-Co powder produced at the spark points reacted with water and 36.2% of carbon in WC-Co powder was changed into CO2 and CO gases by dicarburization while metallic components were partially oxidized.
2) The Aluminum powder reacted with OH-radical and formed Al(OH)3. The reaction took place in short supply of OH-radical by 20.1 % for its theoretical weight at the spark points.
3) The Tungsten Carbide was decarburized by its autolysis at the spark points in the oil medium. 11.4% of carbon was decarburized.抄録全体を表示PDF形式でダウンロード (1748K) -
下飯坂 潤三, 中塚 勝人, 吉田 洋一, 山内 隆夫1977 年 24 巻 4 号 p. 118-122
発行日: 1977/06/05
公開日: 2009/12/04
ジャーナル フリーMagnetite powders were prepared by coprecipitation method, and followed by coating of monomolecular oleate ion. The kerosene base magnetic fluids were obtained by dispersing the powders in kerosene. In this paper, the effects of temperature on the chemical stability of surface-coated magnetite, the magnetic properties of magnetic fluid and its viscosity were examined.
The results obtained are as follows: (1) The surface-coated magnetite is oxidized to a-hematite in the air at about 200°C because of combustion of oleate. (2) The change in the magnetization of magnetic fluid with temperature corresponds to that of magnetite powders. This means that the surface-coated magnetite is fairly stable in kerosene against the change in temperature. (3) Considering that the surface-coated magnetite contains a slight amount of non-magnetic part, the magnetization curve can be explained by Langevin's theory. (4) The magnetic fluids, whose magnetite fractions are less than 0.65 g/ml, show Newtonian flow. For the dependence of temperature on the viscosity of those fluids, Andrade's equation is applicable to the region of 20°C-80°C.抄録全体を表示PDF形式でダウンロード (354K) -
小川 敏夫, 脇野 喜久男1977 年 24 巻 4 号 p. 123-127
発行日: 1977/06/05
公開日: 2009/12/04
ジャーナル フリー(1) The temperature property of resonant frequency of Pb(Sn1/2Sb1/2)O3-PbTiO3-PbZrO3 ternary system was studied, and it was found that the three dimensional expression, composition-frequency constant-temperature, would give us better scope than the two dimensional expression; e.g. the composition- temperature coefficient of resonant frequency, which has been widely used.
(2) The composition which gives minimum frequency constant was constant value independently modes of vibration, and it was found that the mixing ratio of ferroelectric tetragonal and rhombohedral phase was approximately 1 to 1 at this composition which was considered as the center of morphotropic phase boundary.抄録全体を表示PDF形式でダウンロード (1717K) -
加藤 哲男, 草加 藤司1977 年 24 巻 4 号 p. 128-134
発行日: 1977/06/05
公開日: 2009/12/04
ジャーナル フリーThe mechanical properties of 25%Cr-Ni sintered stainless steels were studied in comparison with sinterability originating in α/γ phase constitutions.
The results were summarized as follows:
(1) The highest tensile strength was obtained at the ratio of α/γ phase of about 2 : 1, and the resultant ductility was also relatively good because of promoted sinterability for compacts.
(2) The resistance to impact showed the same change as the ductility with the phase constitution, though the low temperature brittleness was observed in sintered materials containing 6% or less of Ni.
(3) The fatigue strength also exhibited the highest value in the above-mentioned two phase range in relation to matrix hardness, while the endurance limit ratio was 0.3-0.4, and getting a little larger in the vicinity of the α-single phase field.
(4) The tensile strength at temperature over 600°C was independent of the phase constitution and improved with the increase of Ni. The effects of Ni on the creep rupture strength was in general larger than that on the short time hot-tensile strength.抄録全体を表示PDF形式でダウンロード (3846K)
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