巻号一覧
65 巻, 10 号
選択された号の論文の11件中1～11を表示しています
- |<
- <
- 1
- >
- >|
-
山田 健太郎, 里 達雄2001 年 65 巻 10 号 p. 897-902
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーThe effects of various quenching conditions on both the pre-aging at room temperature(R.T.) and subsequent two-step aging behavior of an Al-Mg-Si alloy were investigated mainly by electrical resistivity and hardness measurements. Three types of quenching methods; i.e. water-quenching(W.Q.), step-quenching (S.Q.) and the first pre-aging treatment at 373 K were used before the subsequent two-step aging treatment. The results were discussed in terms of the role of quenched-in excess vacancies in the early stage of precipitation (i.e. Si-rich clusters and GP zones). The results clearly indicate that the quenched-in excess vacancies are trapped inside GP zones during the first pre-aging at 373 K. This effect suppresses the Si-rich cluster formation in the second pre-aging at R.T. and resultantly the negative effect in the final aging at 453 K. It is, therefore, important to control the heat treatment sequence for Al-Mg-Si alloys so that the quenched-in excess vacancies are more associated with the GP zones, the effective nucleation sites for the β″ phase, before the formation of the Si-rich clusters which are non-effective nucleation sites for the β″ phase.抄録全体を表示PDF形式でダウンロード (474K) -
土山 明美, 南 守, 嶋 由加里, 高谷 泰之, 林 安徳, 増田 正孝, 蓮山 寛機2001 年 65 巻 10 号 p. 903-909
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーThe purpose of this study is to improve the corrosion resistance and to examine the electrochemical behavior of Diamond-like carbon (DLC) films. DLC films were prepared by the ionization deposition method with different film thickness, in which benzene (C6H6) was used as precursor gas. The film thickness was changed from 106 to 637 nm and the bias voltage was applied at −1.0 and −2.0 kV. The electrochemical corrosion tests were performed by potentiodynamic anodic polarization, potentiostatic polarization and galvanostatic polarization techniques in 3 mass%NaCl aqueous solutions open to the air at 333 K. The corroded surfaces of DLC/Al after the galvanostatic polarization measurements were observed by a scanning electron microscope. We also examined the adhesion of films using a tensile pull-off tester. In this study, the influence of the preparation conditions on the corrosion resistance of DLC/Al are reported from a study of electrochemical properties. It is found that the corrosion resistance of DLC/Al samples is superior with decreasing film thickness. The corrosion resistance of DLC prepared at Vb=−2.0 kV is more superior to that at Vb=−1.0 kV with similar thickness. The adhesive strength of films is higher for the thinner films and this tendency correlated with the corrosion resistance by electrochemical tests.抄録全体を表示PDF形式でダウンロード (1045K) -
山田 隆志, 浅井 滋生2001 年 65 巻 10 号 p. 910-915
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーFor conventional composite platings, mechanical agitation has been indispensable. In this study, a new method of composite platings has been developed, where a high magnetic field is imposed in the direction parallel to an electrolytic current instead of mechanical agitation. The method provides a micro agitation in the vicinity of a plating surface. It is noticed that the micro agitation aligns particles to the magnetic field direction in a deposited film as well as homogenizing them. The mechanism of aligning particles is discussed, which is based on the generation of microscopic eddy motion around each particle due to the interaction of an imposed magnetic field and an electrolytic current distorted by the existence of non-conducting particles.抄録全体を表示PDF形式でダウンロード (953K) -
宇佐美 徹, 赤尾 昇, 原 信義, 杉本 克久2001 年 65 巻 10 号 p. 916-921
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーAn oxygen sensor with a Ag·YSZ (ZrO2-8 mol%Y2O3) composite thin film electrode deposited on a YSZ disk by ion-beam-sputtering (IBS) was developed. Compositions of the thin films tested were Ag-10 mol%YSZ and Ag-30 mol%YSZ. The performance of the oxygen sensors was examined at temperatures between 573 and 673 K. The mechanism of electrode reactions was inferred on the basis of the results obtained by an AC impedance method. The oxygen sensor with the Ag·YSZ composite thin film electrodes showed the Nernstian response in 1.0% oxygen at temperatures higher than 593 K. The lowest temperature for the Nernstian response was lower by 25 K than that reported for the sensor with a Ag thin film electrode. After a change in oxygen concentration, the response time of the sensor with the Ag-10 mol%YSZ electrode was shorter than that with the Ag-30 mol%YSZ electrode.抄録全体を表示PDF形式でダウンロード (514K) -
上村 隆之, 山下 正人, 内田 仁, 幸 英昭2001 年 65 巻 10 号 p. 922-928
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーThe correlation between corrosion rate and compositions of crystalline corrosion products formed on weathering steels exposed to different amount of air-borne sea salt particles has been investigated by the X-ray diffraction method. The mass ratio (α⁄γ) of crystalline α-FeOOH to γ-FeOOH, in the rust formed on the weathering steels exposed at an industrial environment increases with an increase in exposure duration. The ratio α⁄γ is closely related to the corrosion rate in environments when the amount of air-borne salt is less than 0.2 mg NaCl/dm2/day. However this is not the case in seaside environments with higher amount of air-borne salts. The mass ratio (α⁄γ*) of crystalline α-FeOOH to the total mass of γ-FeOOH, β-FeOOH and Fe3O4, in the rust formed on the weathering steels is related to the corrosion rate even in seaside environments certainly more than 0.2 mg/dm2/day of air-borne sea salt particles. When the ratio α⁄γ* is more than 1, the higher corrosion rate more than 0.01 mm/y is not observed. The ratio α⁄γ* is expected to be an index for evaluating the corrosion resistance of the weathering steels even in atmosphere containing higher salt content.抄録全体を表示PDF形式でダウンロード (420K) -
伊藤 義康, 安藤 秀泰, 須山 章子, 新藤 尊彦2001 年 65 巻 10 号 p. 929-934
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーTungsten/copper coatings were developed using plasma spraying techniques for electric arc resistant. However, the mechanical properties of plasma sprayed coatings, which had an important effect on the adherent strength etc., were not clarified. Two kinds of free-standing tungsten/copper coatings, which were produced by an atmospheric plasma spraying (APS) and a low pressure plasma spraying (LPPS), were machined from the thick coatings and were used for experiments. The Young’s modulus, Poisson’s ratio and four-point bending strength were measured at room temperature. The experimental results suggested that the volume fraction of tungsten or copper, porosity and oxide content had an important effect on the mechanical properties. Namely, the high Young’s modulus, high Poisson’s ratio and high bending strength could be obtained from the tungsten/copper coatings produced by LPPS process, because of the low porosity and low oxide content.抄録全体を表示PDF形式でダウンロード (1406K) -
稲葉 智之, 深山 敏郎, 張 平祥, 佐藤 充典, 前田 弘2001 年 65 巻 10 号 p. 935-940
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーAg-sheathed Bi2223 multifulamentary tapes (7 and 19 filaments) with and without Sr6V2O11(SVO) barriers have been prepared by the powder-in-tube method. The SVO barrier layers are arranged in three different configurations as inside (7 & 19SV10), outside (7 & 19SV01), and inside-outside (7 & 19SV11) of each filament. All of the barrier tapes have much higher critical-current density Jc than the non-barrier tapes (7 & 19SV00). In these cases, the compound SrCO3 contaminated in the process of SVO preparation must be eliminated in the inside-barrier tapes, and a thick-walled Ag tube must be used in the inside-outside barrier tapes with thicker barrier layers. This result will overcome the serious problem of the decrease in Jc in barrier tapes obtained so far. Furthermore, the inside barrier configuration will be possible using only SVO. The increase in Jc will be due to the enhancements of the Bi2223 phase formation and its crystal alignment by the reaction of the inside-coated SVO with a Bi-oxide core for the inside- and inside-outside barrier tapes (SV10 and SV11) and due to the reduction in oxygen partial pressure at the Bi-oxide core site during the heat treatment for the outside-barrier tapes (SV01). Furthermore, for all the barrier tapes, the transport a. c. losses at 77 K in self field are lower than those of the non-barrier-tapes. These results suggest that SVO will be one of the most important candidates for a resistive barrier with the view of a. c. applications. The inside-barrier tapes, especially, will permit the tape to be fabricated with ease and provide good potential for improving the overall Jc.抄録全体を表示PDF形式でダウンロード (545K) -
深山 敏郎, 稲葉 智之, 佐藤 充典, 前田 弘2001 年 65 巻 10 号 p. 941-945
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーWe have developed Ag-sheathed multifilamentary Bi2223 ((BiPb)2Sr2Ca2Cu3Ox) tapes with Sr6V2O11(SVO) barriers. The superconducting properties of the critical current density, Jc and a. c. losses of the tapes strongly depend on the purity of SVO, especially on the residue of SrCO3 in it. In order to examine the behavior of an SVO barrier in detail, we prepared pellet samples with seven layers, which were stacked by barrier and Bi2223 layers one after the other, and examined the reaction between them. The five kinds of barrier layers, such as SrCO3, Sr6V2O11(6-2SVO), 5 and 10 mass%V2O5-added 6-2SVO, and Sr3V2O8 (3-2SVO), were used. The pellet samples were heat-treated at 1113 K for 72-360 ks in air. In the barriers of SrCO3 and 6-2SVO, including the residue of SrCO3, the large Bi2212 (Bi2Sr2Ca1Cu2Ox) grains are grown perpendicular to the interface to form the Bi2212 layers with a thickness of about 100 μm by the reaction between the barrier and Bi oxide. The majority of the Bi-oxide layers are composed of Bi2223 fine grains parallel to the interface. The thickness of the formed Bi2212 layers decreases when the content of SrCO3 in the barriers is decreased. In the reaction, SrCO3 reacts with the Bi oxides, and the elements of Pb and Cu diffuse and distribute homogeneously in the barrier layers. The residue of SrCO3 in 6-2SVO decreases obviously when the additional content of V2O5 is increased. In the 6-2SVO barriers with 5 and 10 mass% added-V2O5, only the very fine Pb oxide grains of (Sr, Ca)2PbO4 are precipitated in a row along the interface. No precipitation occurs for the 3-2SVO barrier. The 6-2SVO is stable, and the 3-2SVO is transformed into the 6-2SVO phase during the heat treatment. We can conclude that, for the use of 6-2SVO as a barrier, it is very important to remove the residue of SrCO3 in the 6-2SVO to prevent the formation of Bi2212 layers and, for that purpose, a small addition of V2O5 is effective.抄録全体を表示PDF形式でダウンロード (752K) -
山田 毅, 都筑 隆之, 佐藤 広明2001 年 65 巻 10 号 p. 946-954
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーA plasma-sprayed preform was newly developed to make the fiber distribution uniform and to improve the cavitation resistance of superplastic-formable titanium matrix composites (TMCs) sheets (SiC/Ti-4.5Al-3V-2Fe-2Mo mass%) during superplastic deformation. The microstructure and tensile strength of the TMCs processed with sprayed preforms (spray composites) were investigated. Sprayed preforms were manufactured by low-pressure-plasma-spraying under an Ar-gas pressure of 0.013 MPa using a matrix alloy powder with a particle diameter of less than 150 μm. The spray composites were fabricated through a foil/fiber/foil process using matrix sheets 0.15 mm in thickness and 4-ply sprayed preforms, and they were consolidated by hot isostatic pressing under an Ar-gas pressure of 150 MPa at 1023 K for 2 h. The sprayed area in the matrix of the sprayed composites consists of three typical structures resulting from the difference in diameter of the powder-particles, which can strongly affect the powder melting conditions. The tensile strength of the spray composite was less than that of TMCs processed with woven preforms (woven composite). This was due to hydrogen embrittlement of sprayed deposits in the spray composite, which had a hydrogen content of 0.0246 mass%. To reduce the hydrogen embrittlement, sprayed preforms were heat-treated in a vacuum at 873 K for 1 h before consolidation. As a result of this treatment, the hydrogen content of the sprayed deposit was reduced to 0.0007 mass%. The tensile strength of the spray composite was also improved, attaining the same strength as that of the woven composites. The tensile strength of the SiC fibers gradually decreased through spraying, heat treatment and consolidation. This, however, did not strongly affect the tensile strength of the spray composite.抄録全体を表示PDF形式でダウンロード (2054K) -
棚橋 浩之, 太田 順子, 内田 浩, 逸見 義男, 笠間 昭夫, 松原 覚衛2001 年 65 巻 10 号 p. 955-960
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーA formation process of the CeFe3CoSb12 thermoelectric materials with a filled skutterudite structure prepared using the gas-atomized powder was studied. Fine powder particles were prepared by a fast Ar gas jet and characterized. It was found that these particles consist of the CeFe3CoSb12, FeSb2, FeSb and Sb. The differential scanning calorimetry curve indicates that thermoelectric materials were sintered through two exothermic reactions, i.e. the low-temperature one probably corresponds to the oxidation of Sb and the high-temperature one matches the skutterudite phase formation from latter three phases. Sintering conditions were adjusted in order to reduce the Sb oxidation and to ensure the skutterudite phase formation. As the result of thermoelectric measurements, the Seebeck coefficient increases, and the both electric conductivity and thermal conductivity decrease in the temperature range 300-850 K mainly with decreasing the residual Sb in the sintered materials. The maximum dimensionless figure-of-merit of 0.63 was obtained for the most improved specimen at 700 K.抄録全体を表示PDF形式でダウンロード (993K) -
末吉 秀一, 丸野 智仁, 山本 浩市, 平田 好洋, 鮫島 宗一郎, 内田 秀, 濱渦 修一, 栗田 澄彦2001 年 65 巻 10 号 p. 961-966
発行日: 2001年
公開日: 2008/04/24
ジャーナル フリーProcessing of continuous ceramic fiber/iron alloy composite by powder metallurgy was investigated. The preparation of continuous ceramic fiber/iron alloy composite is feasible by hot isostatic pressing (HIP) of a laminate of iron alloy powder sheets prepared from a doctor blade method and continuous ceramic fiber sheets. It is necessary to choose suitable temperature and pressure which enable iron alloy to penetrate into yarn through the small openings between the filaments. The continuous ceramic fiber/iron alloy composite in which the filaments are distributed uniformly can be produced by choosing adequate combination of the thickness of iron alloy powder sheet and the number of continuous ceramic fiber sheet.抄録全体を表示PDF形式でダウンロード (1731K)
- |<
- <
- 1
- >
- >|