巻号一覧
27 巻, 3 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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北條 純一, 加藤 昭夫1980 年 27 巻 3 号 p. 71-76
発行日: 1980/04/25
公開日: 2009/05/22
ジャーナル フリーFine WC powder obtained by a vapor phase reaction (f-WC, -0.07μ) and commercial WC powder (c-WC, -l μ) were sintered at 1100-1500°C in hydrogen and at 1500°C and 1800°C in vacuum with emphasis on the particle size-effect on their sinterabilities.
The sintering of both f-WC and c-WC powders began at about 1100°C. The densification of powder compacts proceeded rapidly in the early period and stopped substantially after 0.5 hr. This rapid densification seemed to be due to a particle rearrangement. A remarkable grain growth was observed shortly after this initial densification. The coarser c-WC powder showed the very similar sintering-behavior to the finer f-WC powder. This suggests that the smaller particles (-0.1 μ) contained in c-WC powder may play an important role in the densification. The sinterability of WC particles was higher in hydrogen than in vacuum at 1500°C, for which the difference in the chemical behavior of oxide layer (vaporization as oxide under vacuum and reduction in hydrogen) may be responsible.抄録全体を表示PDF形式でダウンロード (3013K) -
鈴木 寿, 林 宏爾, 久保 裕1980 年 27 巻 3 号 p. 77-81
発行日: 1980/04/25
公開日: 2009/05/22
ジャーナル フリーIt was shown in a previous report by the present authors that high temperature transverse-rupture strength of TiC-Mo2C-Ni cermet was highly improved by the addition of a small amount of ZrC or HfC. Therefore, in the present study, the strengthening mechanism was investigated mainly for TiC-Mo2C-(1-40)%Ni cermets containing 1 mol%ZrC.
It was found that the binder phase can be plastically deformed less easily in ZrC contained alloys, so that the crack initiation load at carbide/carbide interfaces increases and the growth rate of stable cracks decreases. It was suggested that the decrease in diffusivity of the binder phase is responsible for the strengthening of the ZrC contained alloy, rather than the solution hardening in carbide phases.抄録全体を表示PDF形式でダウンロード (1540K) -
三浦 秀士, 坂本 愛一郎, 徳永 洋一1980 年 27 巻 3 号 p. 82-87
発行日: 1980/04/25
公開日: 2010/07/12
ジャーナル フリーThe pore shape in various sintered iron compacts has been found to affect the Young's modulus measured by the resonance method. The Young's moduli of sintered iron and steel compacts are, therefore, discussed in this paper, taking the pore structure into account.
The Young's moduli of sintered steel compacts are not much affected by either the addition of graphite, copper and nickel, or the change of matrix structure due to the heat treatments, but are affected mostly by the pore structures depending upon the types of iron powder.
The value of Young's modulus of commercial sintered iron is lower than that of carbonyl sintered iron which satisfies the equation proposed by Mackenzie; E/E0≅1-2ε, where E is Young's modulus of sintered iron or steel, E0 that of bulk material, and ε the porosity. This lowering of the Young's modulus is attributed to the difference in pore shape. Using proposed empirical constants a, b which express some character of the pore shape, the relation between Young's modulus and the porosity can in general be expressed as E/E0= b/a+ε(1-2ε). The change of Young's modulus for various iron powder materials used can be clearly explained by this equation. The value of a which is determined to be from 0.4 to 0.7 in the experiment takes a larger value as the pore shape becomes spherical. Actual values of a and bare related as b=1.1a.抄録全体を表示PDF形式でダウンロード (3195K) -
宇津木 弘, 遠藤 敦, 柏木 敏子, 市村 嘉郎1980 年 27 巻 3 号 p. 88-94
発行日: 1980/04/25
公開日: 2009/05/22
ジャーナル フリーThe pyrolysis of the surface-treated silica gels with several alcohols, whose surfaces had been confirmed to have a hydrophobic nature, was studied by the analysis of the vapors evolved at each temperature up to 800°C through the Quadru Pole Mass Spectrometer. It was found that the pyrolysis of the surface group was performed at 450°C and the silica gels thus thermally decomposed reverted to a hydrophilic nature. The surface area of the original silica gel activated at the temperature up to 500°C was found to be invariant, whereas that of the silica gels activated at higher temperature decreased by the sintering or solidification with increasing temperature. The silica gel activated at 1000°C had a quarter of the surface area of the original silica gels. The surface area of silica gels treated with the alcohols was small in comparison with that of original silica gels, but it increased after the activation at 250°and 350°C. When these surface-treated silica gels were heated at 450°C, they had the nearly same surface area as the one of original silica gel. The argon adsorption isotherms at 77°K on these silica gels showed a good agreement with the one of the original silica gel over whole range of relative pressure. Therefore it was considered that the geometric surface structure like pore of the substrate was invariant through the surface-treatment, and the nature of the surface of silica gel was changed from hydrophilic to hydrophobic through these treatments.抄録全体を表示PDF形式でダウンロード (478K) -
田口 秀樹, 高橋 弓弦, 松本 忠恕1980 年 27 巻 3 号 p. 95-97
発行日: 1980/04/25
公開日: 2009/05/22
ジャーナル フリーThe nonstoichiometric perovskite LaMnOx was prepared under different conditions. LaMnOx was ground with a small amount of water. Then the space between electrodes was smeared with the muddy samples. After drying the samples, the electrical resistivity was measured at 27°C in the relative humidity range from 0 to 100%. The electrical resistivity exponentially decreased with increasing relative humidity. From this decrease, it is assumed that the electrical conductivity is based on the ionic conductivity of the adsorbed water.抄録全体を表示PDF形式でダウンロード (228K)
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