巻号一覧
62 巻, 6 号
選択された号の論文の14件中1～14を表示しています
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今清水 雄二, 渡辺 慈朗1998 年 62 巻 6 号 p. 497-504
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーCopper-nickel dilute alloy crystals with [111] orientation were pulled from the melt containing 0.02, 0.05, 0.1, 0.2 and 0.5 at% nickel in a stream of purified argon gas under a given condition by the Czochralski method. The distribution and density of grown-in dislocations were examined by etching the (111) faces of six transverse cross-sections. The effects of nickel addition on the dislocation formation are discussed by referring to the previous work on copper-aluminium and copper-gold dilute alloy crystals.
(1) In Cu-0.02, 0.05 and 0.1 at%Ni alloy crystals, linear arrays of slip dislocations along ⟨1\bar10⟩ directions were formed prominently, and the mean dislocation densities in those crystals became higher than that in copper crystals.
(2) In Cu-0.2 at%Ni alloy crystals, a substructure consisting of long subboundaries and dislocation clusters was introduced inhomogeneously, while slip dislocations were scarcely formed, and the dislocation densities were generally high.
(3) In Cu-0.5 at%Ni alloy crystals, short subboundaries and dislocation clusters were distributed rather homogeneously, and the dislocation density became higher.
(4) It was found that the effect of small additions of nickel on the formation of slip dislocations and the dislocation density was quite different from that of the addition of aluminium or gold. On the other hand, the formation of dislocation substructures in crystals containing nickel more than 0.2 at% could be attributed to trapping of inclusions at the non-planar solid-liquid interface instabilized due to constitutional supercooling, in the same way as in the crystals containing aluminium or gold by more than a certain critical concentration.抄録全体を表示PDF形式でダウンロード (1472K) -
大西 正已, 李 賛揆, 尹 在弘, 下 敏唯1998 年 62 巻 6 号 p. 505-509
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーA moving phase boundary under the influence of binary reaction diffusion has been represented by the following flux equation;
(This article is not displayable. Please see full text pdf.)
\ oindentIf Ji is identical with the flux defined by Fick’s first law, the boundary never moves. Other types except the Fick’s flux, i.e., the fluxes relative to the phase boundary are introduced. Interfacial reaction and a local equilibrium state as non-equilibrium phenomena are discussed from the stand point of the flux balance at the phase boundary, Usually, interfacial reaction causes the boundary migration controlled by diffusion. The migration depends on the magnitude of a free energy difference developed at the boundary. As a special case the boundary moves under the existence of a local equilibrium state at the boundary without the interfacial reaction. The movement at the state arises from the Kirkendall effect.抄録全体を表示PDF形式でダウンロード (530K) -
佐貫 須美子, 高松 威夫, 真嶋 宏1998 年 62 巻 6 号 p. 510-518
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe applicability of high temperature hydrolysis method to the precipitation of spherical fine particulates of CuO from aqueous Cu(II) ammine solution was investigated by examining various conditions.
Although Cu(II) ammine complexes are stable at ambient room temperature, they are decomposed to CuO by aeration at elvated temperatures, loosing ammonia gas outside the solution system. However, it is impossible to presipitate spherical fine CuO particulates by high-temperature hydrolysis of Cu(II) ammine solution. To obtain spherical fine particles of CuO, it is necessary to remove excess ammonia in the solution by aeration at room temperature, followed by the high temperature hydrolysis without agitation of the solution. The presence of ammonium salts in the solution system is indispensable to obtain sperical particles. The CO2 gas contained in air is useful to form ammonium salt necessary for spherical CuO precipitation. The increases in aging time, ammonia concentration and ammonium salt concentration play an importantrole to increase the resultant CuO particle size. Also, those factors affect undesirably the size distribution of CuO and lower precipitates yield.
Anions, such as sulfate and carbonate, do not show distinct effect on spherical CuO precipitation, however carbonate ions show the increasing effect of particle size. On the other hand, chloride ions disturb the formation of spheritical CuO.
This method was found to be applicable to leach solution of copper metal with Cu(II) ammine solution to produce spherical fine CuO particulates.抄録全体を表示PDF形式でダウンロード (2421K) -
佐貫 須美子, 高松 威夫, 真嶋 宏1998 年 62 巻 6 号 p. 519-526
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーIn a previous paper, the present authors reported that the preparation of spherical fine CuO powders was achievable by applying hydrolysis method at elevated temperature to Cu(II) ammine solution.
Based on this finding, the effect of hydrolysis reaction rate on CuO particulate diameter was investigated in this study. It was elucidated that the precipitation of spherical CuO particulates proceeds according to a typical building up mode: super-saturation, nuclear formation and crystal growth.
Generally, the increase in NH3 concentration, Cu(II) concentration under the constant ratio of [CuSO4]⁄[Ammonia]=8.5, and (NH4)2SO4 concentration at the constant ratio of [Ammonia]+2[(NH4)2SO4]=1.7×102 mol·m−3 resulted in the decrease of crystallization rate. The concentration-dependence in crystallization rate was more sensitive at 353 K than 373 K. The apparent activation energy of 11.7 kJ·mol−1 obtained in the temperature range 363∼378 K suggested mass transfer mechanism.
Mean diameter of CuO spherical particles and their size distribution increased with an increasing ammonia, CuSO4 and (NH4)2SO4 concentrations, on the contrary, the yield of CuO decreased. No differences of particle size were detected by the change of temperature from 353 to 373 K.
There existed a correlation among crystalliration rate, mean particle size and size distribution range when the temperature was kept constant. The increase in crystallization rate resulted in the decrease in particle size.抄録全体を表示PDF形式でダウンロード (1194K) -
藤本 慎司, 柴田 俊夫, 山田 智之1998 年 62 巻 6 号 p. 527-533
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーType 304 stainless steel was irradiated with ultraviolet light of wavelength 325 nm in 3.5%NaCl solution to suppress the pitting corrosion susceptibility. The uv irradiation during passivation at +100 mVAg/AgCl for 600 s and during the potentiodynamic pitting corrosion test shifted the pitting potential in noble direction. The more potential shift in noble direction was observed for uv irradiation during passivation. The pitting corrosion induction period for potentiostatic pitting corrosion test was also analysed in terms of the birth and death stochastic probability process to obtain the pitting generating rate, λ, and repassivation rate, μ. λ was lowered by a factor of about 5 after uv light exposure during passivation prior to potentiostatic polarisation, whereas μ indicated almost no change. On the other hand, the uv exposure during pit generation period brought about only a small improvement on both λ and μ. An X-ray photoelectron spectroscopy revealed the chromium enrichment in the passive film after the exposure of uv light during passivation, which leads to suppress the pit initiation rate. The uv irradiation on stainless steels in aqueous environments revealed to improve the corrosion resistance due to a modification of the passive film by the quantum effect of photo-excitation.抄録全体を表示PDF形式でダウンロード (690K) -
澁谷 秀雄, 森永 正彦, 菊池 圭一1998 年 62 巻 6 号 p. 534-541
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーNodular corrosion takes place in cladding tubes of the boiling water reactor. In order to understand the mechanism of the nodular corrosion, a series of corrosion tests was performed with pure Zr and Zr-M binary alloys (M=Sn, Fe, Cr, Ni) by exposing them to the steam environment of 773 K and 10.3 MPa. The chemical composition of the oxide layer formed on the specimen surface was analyzed using X-ray photoelectron spectroscopy. As a result, it was found that the distribution of alloying elements, M, in the oxide layer was relatively uniform in the case of uniform corrosion, whereas it was very non-uniform in the case of nodular corrosion. For example, in the latter case, alloying elements such as Cr and Sn were condensed mainly in the outer surface of the oxide layer. Such a non-uniform distribution of alloying elements will not be arisen from the heterogeneous distribution of alloying elements in the mother alloy, but will be introduced to the oxide layer on the alloy in the course of corrosion. The segregation of alloying elements will disturb the uniform growth of the oxide layer, resulting in the onset of nodular corrosion on the surface.抄録全体を表示PDF形式でダウンロード (714K) -
谷口 滋次, 本瓦 成人, 柴田 俊夫1998 年 62 巻 6 号 p. 542-550
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe oxidation behaviour of TiAl (36.5 mass%Al) has been studied at 1100 K and 1200 K for 100 ks in a flow of O2, O2-CO2 mixtures or CO2 under atmospheric pressure. The structure of the scales formed in pure O2 atmosphere is very similar to that reported in the literature. The mass gain due to the oxidation significantly increases with increasing partial pressure of CO2 in the O2-CO2 gas mixtures. However, the mass gain in 100%CO2 is about a half of that in O2-90%CO2 at 1200 K. The oxidation enhanced by the addition of CO2 is attributable to (1) the provisional formation of TiC particles, which disturb the continuity of the initially formed Al2O3 scale and (2) the formation of a very porous layer in the thick scale next to the substrate by TiC particles enriched there, which prevent the sintering of oxide grains.抄録全体を表示PDF形式でダウンロード (1364K) -
水内 潔, 武内 孝, 福角 真男, 杉岡 正美, 永井 宏1998 年 62 巻 6 号 p. 551-556
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーIn order to get net-shape metal-matrix-composites, the LCCS process which is the combination of low pressure casting and combustion synthesis has been proposed. By this process, net-shape Al/Al3Ti MMCs, which contain few cavities, have been produced. Microstructures and mechanical properties of the produced samples were examined. The effective infiltration of molten Al into the Al-Ti mixed powders was observed at the Al mixing ratios higher than 50 at%. On the other hand, the Al mixing ratios less than 50 at% prevents the infiltration of molten Al. The critical mixing ratio, at which the infiltration can complete, is calculated by using a simple formula as a function of the relative density of Al-Ti mixed powders. In the mixing ratio of Ti powder less than the critical mixing ratio, the volume fraction of Al3Ti in the MMC increases with increasing Ti powder content.抄録全体を表示PDF形式でダウンロード (761K) -
西薗 和博, 森 信幸, 大城 桂作1998 年 62 巻 6 号 p. 557-562
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーBoth suprerconducting and mechanical properties of Y-Ba-Cu-O superconducting oxide (YBCO) can be improved by fine Ag particles dispersed in Y123 (YBa2Cu3O7−x) matrix. The growth process of YBCO/Ag composite was investigated to clarify the solidification condition for producing columnar 123 crystals with Ag particles. Plate-like YBCO/Ag composites were horizontally solidified using Y123 +15 mass%Ag particles and Y123+Y2BaCuO5 (Y211)+15 mass%Ag particles as starting materials. The distribution of Ag particles and gas holes were quantitatively measured and the changes in thermal conductivity and the effective temperature gradient were estimated by applying the rule of mixtures. Columnar 123 crystals developed under the critical solidification condition of G>6×109·R for YBCO/Ag composites, while G>4×109·R for Ag-free YBCO, where G was temperature gradient (K/m), and R was solidification rate (m/s).抄録全体を表示PDF形式でダウンロード (893K) -
西薗 和博, 黒木 高志, 新清 文紀, 森 信幸, 大城 桂作1998 年 62 巻 6 号 p. 563-569
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe distribution of 211(Y2BaCuO5) and Ag particles in the columnar 123(YBa2Cu3O7−x) crystal of YBCO/Ag composites solidified unidirectionally was investigated to clarify the peritecto-monotectic solidification mechanism. The fabricated 123 crystal has a faceted cell and a band structure of 211 particles at the center of the cell, because of radial solute diffusion layer at the cell tip where 211 particles can’t sufficiently dissolve into the melt. Ag-free region was also formed at the same central region of the 123 cell by pushing of Ag particles, which sizes are under a critical radius (rc), by the 123 growth interface. The relation between r0 and growth rate Ri (: the following Ra or Rc) of faceted planes was given by the equation: Ri=0.52⁄rc. In the Ag added hyperperitectic YBCO, the amount of the 211 particles in the 123 phase was larger in the Ag-rich region than in the Ag-free region because the amount of 123 phase in the Ag-rich region was smaller than that in the Ag-free region. Therefore, the distribution of 211 particles in the 123 phase takes a duplicated structure. The growth direction of the cell tip was obtained by analyzing the above band structures of Ag-free regions or 211-rich regions which correspond to the growth trace of cell edges. From the measured crystallographic orientation of the cell, the relation between Ra, Rc and R are Ra(Rb)=0.66R and Rc=0.54R, where R (μm/s), Ra, and Rc (μm/s) are macro-growth rate of each faceted plane, respectively.抄録全体を表示PDF形式でダウンロード (1264K) -
弦間 喜和, 鈴木 秀和, 恒川 好樹, 奥宮 正洋, 毛利 尚武1998 年 62 巻 6 号 p. 570-576
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThis study is aimed at examining the influence of ultrasonic vibration on the in-situ formation of stable oxides, Al2O3 and MgAl2O4, from SiO2 particles added as an oxygen source in melt stirring. The preheated SiO2 particles were added on a molten Al or Al-Mg alloy surface and stirred at 1073 K in an Ar atmosphere. The ultrasonic vibration was then transmitted to molten metal through a ceramic plate. The SiO2 particles are not transferred into the molten Al by melt stirring without ultrasonic vibration. With ultrasonic vibration, the SiO2 particles, which have been transferred into the molten Al due to the improved wettability, change to stable Al2O3. The transferred SiO2 particles into the molten Al-Mg alloy change to MgAl2O4 and Al2O3. The application of ultrasonic vibration to melt stirring makes not only the wettability improve, but also the cracks in the particles grow, which arise from the volumetric shrinkage accompanied with the change from SiO2 to MgAl2O4 and Al2O3. The stable oxides are rapidly formed due to the fast diffusion of Al and Mg through the cracks. The exothermic reactions of MgAl2O4 and Al2O3 formation lead to a temperature rise in the molten Al-Mg alloy, in which the temperature rise of 99 K is approved by applying the ultrasonic vibration. Consequently, the in-situ reactions are promoted further. Gas defects disappear in the solidified Al alloy containing the stable oxides stirred with ultrasonic vibration, in which the particle distribution is also improved.抄録全体を表示PDF形式でダウンロード (1249K) -
宮田 保教, 牛腸 英紀, 登 勇樹, 鎌土 重晴1998 年 62 巻 6 号 p. 577-585
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーAl-Cu alloy with low solute concentration 0.5 mass%Cu is rapidly melted by CO2 laser with high power and solidified unidirectionally with high scanning rate and high cooling rate. Solidification rate and temperature gradient are analyzed numerically by the finite element code MARC. The rapidly solidified dendritic microstructures have been observed in the wide range of growth rates, which have been predicted by the Mullins-Sekerka’s theory. The primary dendrite arm spacing is shown to decrease with V0.5 below 0.1 m/s of growth rate V and to decrease more slowly than V0.5 over 0.1 m/s growth rate.抄録全体を表示PDF形式でダウンロード (1419K) -
清水 史幸, 藤野 茂, 森永 健次1998 年 62 巻 6 号 p. 586-591
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーElectron beam cold hearth refining (EB-CHR) of Ni, Ti-based alloys and refractory metal (Nb, Mo, Ta and W) was performed to examine the refining effect and its ability to produce homogeneous materials in the 2000 kW EB-CHR furnances.
(1) Behavior of gaseous elements in the refractory metals was discussed with taking the volatile parameter, Vp, into the consideration. (2) The evaporation rate of impurities in the refractory metals was in good agreement with actual vapor pressure from the viewpoint of pressure ratio, Pi⁄PNb, Pi⁄PTa. (3) The evaporation rate of the alloying elements in Inconel 718 was discussed in terms of the following properties: vapor pressure, atomic mass, and molten temperature, it was in good agreement with calculated vapor pressure. (4) Actual yielding of aluminum in Ti-6Al-4V alloys was determined by the rate of linear reaction rate, which was discussed in terms of the following properties: aluminum contents of electrode, melting rate, and molten temperature. It was in good agreement with the calculated yielding of aluminum.抄録全体を表示PDF形式でダウンロード (558K) -
長谷 隆司, 渋谷 和幸, 林 征治, 嶋田 雅生, 川手 剛雄1998 年 62 巻 6 号 p. 592-598
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーCritical current densities of double-sheathed Bi2Sr2CaCu2Ox (Bi-2212) multifilamentary octagonal and round wires heat-treated in pure oxygen atmospheres or in mixed atmospheres of oxygen and nitrogen have been measured. These wires have been prepared employing “High Oxygen Pressure Confinement Process” in which the oxygen partial pressure is raised to over 0.1 MPa. The critical current density of the wire heat-treated in the pure oxygen atmosphere degrades with increasing oxygen pressure. On the other hand, the critical current density in the case of heat treatment in the mixed atmospheres is enhanced by optimizing oxygen partial pressure, accompanied by increasing the total pressure. As a typical case, a critical current density of ∼1.0×105 A/cm2 has been realized at 4.2 K in 0 T for multifilamentary round wire of 1.04 mm in diameter. A new model for Bi-2212 crystallization is proposed taking account of high pressure nitrogen inside the wire, which relatively suppresses growth rate of non-superconducting materials and yields a highy oriented crystalline structure.抄録全体を表示PDF形式でダウンロード (830K)
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