巻号一覧
70 巻, 6 号
選択された号の論文の11件中1～11を表示しています
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南部 智憲, 清水 信恵, 江崎 尚和, 湯川 宏, 森永 正彦, 竹市 信彦2006 年 70 巻 6 号 p. 467-472
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーThe Lattice constants of pure niobium metal were measured by in-situ X-ray diffraction method at the temperature of 293 K to 673 K and the hydrogen pressure below 0.3 MPa. The deformation and fracture of niobium metal membrane during hydrogen permeation were treated by the measured lattice strain. The membrane was deformed and fractured easily when about 10% lattice contraction was introduced to it by lowering the hydrogen pressure at 673 K, at which the dehydrogenation reaction progressed smoothly. However, neither deformation nor fracture took place at the temperature lower than 473 K, because the dehydrogenation reaction hardly occurred in such a temperature range. Thus, the principal reason for the deformation or fracture of niobium metal membrane was attributable to the large volumetric contraction during dehydrogenation, the easiness of which, however, depended largely on the temperature.
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曹 奇峰, 土谷 浩一, 原田 泰典, Dacian Tomus, 森井 浩一, 戸高 義一, 梅本 実2006 年 70 巻 6 号 p. 473-477
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーEvolution of surface roughness and microstructure in Ti-50.9 mol%Ni shape memory alloy by shot peening were investigated by X-ray diffractometry and transmission electron microscopy. The crystallite size decreased significantly by shot peening of 30 s and remained essentially unchanged after longer peening. TEM observations of the deformed surface layer revealed the formation of amorphous and nanocrystalline in the samples after shot peening for 20 s. In the area with the lower extent of deformation, {114}B2 deformation twins and thin amorphous bands parallel to the twins were found. It implies that the amorphization occurs preferentially along the twin interfaces.
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上原 朋樹, 五十嵐 伸昭, Rodion V. Belosludov, Amir A. Farajian, 水関 博志, 川添 良幸2006 年 70 巻 6 号 p. 478-482
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーThe transport properties of a single ferrocene have been investigated using the nonequilibrium Green's function formalism for quantum transport and the density functional theory of electronic structures using local orbital basis set. It is found that the conductance of a single ferrocenedithiolate molecule depends on the position of the sulfur atoms. The conductance properties of a metallocene are characterized by the molecular orbitals with the large contribution of metal atom. In the case of ferrocenedithiolate, the orbitals with Fe contribution near Fermi level affect significantly on electron transport. Therefore, the higher conductance through ferrocene will be expected as comparable with magnesocene under applying bias.
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吉川 昇, 中野 雄也, 佐藤 健太郎, 谷口 尚司2006 年 70 巻 6 号 p. 483-488
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーFundamental studies were performed on the reaction kinetics and the microstructures of the reaction products between soda-lime glass and molten Al (and synthesized Al scrap alloy) in order to fabricate a composite material using waste glass and aluminum scrap.
The reaction layer of soda-lime glass with molten Al grew as a function of square root of the reaction time at 700°C, indicating that the kinetics is governed by the mass transfer rate. The following features were demonstrated according to the compositional mapping image of the un-reacted glass, the reacted layer and the metal (Al) matrix:
1. Si was reduced from SiO2 and dissolved into Al, and solidified in the Al matrix. The Si concentration was low in the reacted layer.
2. Na, K also dissolved into Al. However, Na segregated in the un-reacted glass at the reaction interface.
3. Ca oxide in the glass was not reduced with Al, hence Ca was not dissolved into the Al matrix.
4. Mg was distributed in all areas of the glass, the reaction layer and in the Al matrix.
These tendencies were discussed with the thermodynamic consideration.
The amount of Si in the metal layer increased as the decrease in the glass particle size, because of increase in the total area of the reaction surface. The similar results on the reaction kinetics and the microstructures were obtained in the reaction between the wasted glass and the synthesized Al scraps.
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横堀 壽光, 櫛田 隆弘, 大見 敏仁2006 年 70 巻 6 号 p. 489-494
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーThe analytical solution of hydrogen diffusion and concentration around the heat affected zone of weld part was derived by taking account for the effect of residual stress on hydrogen concentration. Based on the theoretical analysis, the sensitivity of hydrogen embrittlement was formulated and it is proportional to DK2, where D is diffusion coefficient, K is stress gradient term of residual stress approximated by linear function. It was in good agreement with that previously obtained by numerical analysis.
This result shows that the law of hydrogen sensitivity is commonly valid independent of boundary condition when the distribution of residual stress is approximately written by linear functions of the distance in the heat affected zone. Furthermore the analysis of the period when hydrogen embrittlement becomes remarkable was conducted. This result enables us to predict the behavior of hydrogen embrittlement at the heat affected zone of weldment.
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岡 利昭, 水関 博志, 川添 良幸2006 年 70 巻 6 号 p. 495-499
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーFuel cells have attracted attention in recent years because they are very energy-efficient. However, we have to face up to a serious problem in that platinum, which is the usual anode electrocatalyst, is readily poisoned by CO. In the case of the Direct Methanol Fuel Cell (DMFC), it is very important to develop new materials for use as electrocatalysts that exhibit good tolerance to CO, since CO is invariably present as an intermediate in the dissociation of methanol. The aim of this study is to examine the mechanism of H2O dissociation and of the CO+OH combination reactions in the CO oxidation process by calculating the adsorption energies and the activation barriers. In the case of Pt-Ru alloys, the activation barrier of the H2O dissociation reaction is almost the same as it is for pure Pt. The activation energy of the CO+OH combination reaction on Pt-Ru alloy is larger than that on pure Pt. Nevertheless, the adsorption energy of H2O is larger than that on pure Pt. On the other hand, the activation barrier and adsorption energies of H2O on Pt-Sn alloy are very close to the corresponding values on pure Pt. Moreover, the activation barrier for the CO+OH combination reaction on Pt-Sn alloy is lower than that on pure Pt.
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長島 伸夫, 松岡 三郎2006 年 70 巻 6 号 p. 500-504
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーThis report describes the nanoscopic strength analysis of low carbon austenitic stainless steel 316NG pre-strained to ±10% and ±20% true strain under tension and compression loading. This strength analysis was conducted, using an ultra-micro, micro and Vickers hardness testers and TEM. TEM observations showed that the micro-structural parameters relevant the analysis are the dislocation cell size, dcel and the coarse slip band spacing, lcsl. 10dcel or 10lcsl shows the position where fine grain strengthening by dislocation cells or slip spacing saturates and the hardness becomes constant. The Vickers hardness, HV, corresponding to the micro strength was expressed as HV=Hv*bas+Hv*sol+Hv*dis+Hv*cel+Hv*csl. Hv*bas is the base hardness, Hv*sol is the solid solution strengthening hardness, Hv*dis is the dislocation strengthening hardness in the dislocation cell, and Hv*cel and Hv*csl are the fine grain strengthening hardness due to the dislocation cell and coarse slip band, respectively. Hv*bas, Hv*sol and Hv*dis were about 100, 50 and 0, respectively, independently of the pre-strain of ±10% and ±20%. Accordingly, the Vickers hardness increment corresponding to the work hardening was equal to the sum of Hv*cel and Hv*csl. In other words, the work hardening due to tension and compression pre-straining up to ±20% is dominated by fine grain strengthening due to the dislocation cell and coarse slip band. This behavior was similar to that obtained in SUS316NG steel pre-strained by cold rolling in the previous study. It is concluded from those results that the work hardening mechanisms in SUS316NG steel are independent of the pre-strain method.
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中村 愼一郎, 中島 謙一2006 年 70 巻 6 号 p. 505-510
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーThis paper develops a theoretical model of material flow analysis (MFA) within the framework of the Waste Input-Output model (WIO) (Nakamura and Kondo). The model is developed based on two fundamental ingredients: yield ratios and the degree of fabrication. In manufacturing process, multiplication of physical inputs by the yield ratios gives the portion that enters physical outputs, with the rest being discarded as process waste without entering outputs. In input-output analysis, the degree of fabrication can be visualized as triangularity of the input coefficients matrix (goods of lower degree of fabrication can enter those of higher fabrication, but the reverse does not hold), which is known to emerge through an appropriate reordering of sectors. Application to the Japanese IO data indicates that the model can provide accurate estimates of the weight as well as the composition of metals (Fe, Cu, Pb, Zn, and Al) used in a passenger car. The model is also used to estimate the major final use categories (household consumption, public consumption, capital investment, inventory investment, and export) of metals.
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小野 正雄, 木下 貴博, Xinsheng Huang, 井口 裕介, 岡安 悟, 真下 茂2006 年 70 巻 6 号 p. 511-516
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーUltracentrifuge experiments were performed on a miscible In-Pb alloy to study sedimentation of constitutional atoms under a strong gravitational field (maximum acceleration: 106 g level, temperature: below melting point (solid), starting state: intermediate α-phase (f.c.t., c0/a0<1), time duration: 30-150 h). The Graded structures were formed in all centrifuged samples, in which, the Pb content continuously increased, and the In content decreased in the direction of gravitational field. For the centrifuged sample of 100 h in time duration, Pb-rich phase (f.c.c.) and In-rich phase (f.c.t., c0/a0>1) appeared at the highest- and lowest-gravitational field sides of the sample, respectively. These observation results showed that the graded structure was continuous in atomic scale, and was formed by sedimentation of constitutional atoms (substitutional atoms). It was also found that the composition change reached steady state within 60 hours. Based on a simulation of sedimentation process, the diffusion coefficient for sedimentation was estimated to be about 8 times larger than that for usual diffusion.
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曽田 繁利, 伊藤 正樹, 野口 浩幸, 北川 裕之, 長谷崎 和洋, 野田 泰稔2006 年 70 巻 6 号 p. 517-520
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーThe large maximum of thermopower as a function of temperature observed for Bismuth Antimony alloy is studied theoretically based on the Boltzmann transport theory of single carrier. The Fermi statistics is fully taken into account, with the chemical potential calculated self-consistently at each temperature from experimental Hall coefficients. It is almost constant at lower temperatures, and begins to increase at T=70 K, where the maximum of the thermopower is observed. The temperature dependence of the calculated thermopower agrees well with the measurements. The occurrence of the maximum is thus shown to be associated with the transition between extrinsic conduction and intrinsic conduction, which provides theoretical confirmation to the known empirical rule.
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森 久史, 野田 雅史, 辻村 太郎, 船見 国男, 東 健司2006 年 70 巻 6 号 p. 521-523
発行日: 2006年
公開日: 2006/06/21
ジャーナル フリーEffects of grain growth due to treated by annealing after thermomechanical treatment on the tensile and fatigue strength in Magnesium alloy AZ31 were reported. It was found that coarse grain generated by secondary recrystallization and tensile and fatigue strength was decreased.
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