巻号一覧
54 巻, 9 号
September
選択された号の論文の7件中1～7を表示しています
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研究
研究
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結城 潤一, 川崎 亮, 曲尾 章, 野口 徹, 別府 潤一, 関 正幸2007 年 54 巻 9 号 p. 627-634
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスThis paper describes a fabrication process of Al/CNT composites and measurement of their mechanical properties. It is a very useful reinforcement for composites since CNT has very high strength and very high Young's modulus. However, it is very difficult to distribute CNT in the metal matrix. Natural rubber, Al powder and CNT precursors were used to improve the distribution of the CNT in Al matrix. CNT distributed mixture with Al powder were obtained using the precursors produced by heat treatment in N2 atmosphere. The Al/CNT mixed powder filled up into Al alloy billets were encapsulated in vacuum atmosphere. Then, the billets were extruded with different extrusion ratios of 5, 10 and 20 at 673K. The composites were observed by optical microscope and FE-SEM. The mechanical properties were evaluated by Vickers hardness and tensile tests. We succeeded in achieving fully densified and finely extruded rod of Al/CNT composites by hot extrusion process. Observation of micro structures after hot extrusion revealed that CNT aligned along the extrusion direction. Vickers hardness and tensile strength obtained were about twice compared to pure Al.抄録全体を表示PDF形式でダウンロード (1354K) -
大原 智, 樋高 英嗣, 張 静, 梅津 光央, 名嘉 節, 阿尻 雅文2007 年 54 巻 9 号 p. 635-638
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスWe report a new method to synthesize cobalt (Co) nanoparticles using supercritical hydrothermal synthesis. An important aspect of supercritical hydrothermal synthesis of nano particles is the ability to create a homogeneous reducing atmosphere by introducing H2 gas. Co aqueous solution with formic acid was pressurized to 30 MPa at room temperature and rapidly heated to 400°C by mixing with supercritical water and then fed into a tubular reactor. The size of obtained Co nanoparticles was about 10nm and its particle size distribution was very narrow. The coercivity force at room temperature of the nanopartricles showed about 90 Oe. In this study, another important aspect of supercritical hydrothermal synthesis is reported; that is, in-situ surface modification of Co nanoparticles with carboxylic acids during crystallization.抄録全体を表示PDF形式でダウンロード (925K) -
Masahiro Yasukawa, Kaoru Ikeuchi, Toshio Kono, Hiroshi Yanagi, Hideo H ...2007 年 54 巻 9 号 p. 639-644
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスSemiconductive La-doped BaSnO3 with a perovskite-type structure was prepared at relatively low temperatures using a polymerized complex method. The Ba-, La-, and Sn-citrate complexes polymerized randomly with citric acid and ethylene glycol were synthesized and then pyrolyzed to form amorphous precursor. The perovskite-type single phase of La-doped BaSnO3 was directly obtained by heating the amorphous precursor at 873 K, owing to the homogeneous distribution of constituent elements Ba, La, Sn on an atomic scale in the polymerized complex. The electrical conductivity σ and Seebeck coefficient S were measured in the temperature range 373∼1073 K for the bulk sample to evaluate the thermoelectric properties. The Ba0.95La0.05SnO3 showed n-type degenerate semiconducting behavior and the thermoelectric power factor S2σ increased from 6.5×10−8 Wm−1K−2 to 1.0×10−6 Wm−1K−2 with increasing temperature.抄録全体を表示PDF形式でダウンロード (1085K)
特集：次世代マグネシウム粉末
総報
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河村 能人2007 年 54 巻 9 号 p. 646
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスPDF形式でダウンロード (133K)
解説
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榎本 清志, 伊牟田 守, 笹嶋 幹雄2007 年 54 巻 9 号 p. 647-652
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスThe research and development project on advanced composite materials & process development for next generation aircraft structures has been performed since FY2003 under the contract with Ministry of Economy, Trade and Industry (METI) in Japan. This project aims to develop innovative lightweight materials & process technologies for civil aircraft structures and consists of 3 technical areas, radiation-curing technology of polymer matrix composites (PMC) structures, structural health monitoring (SHM) technology of PMC structures, and advanced magnesium alloy technology.
In advanced magnesium alloy technology, alloy contents, fabrication process and structure member production technology are being developed about casting alloy technology and powder alloy technology.
In this paper, we introduce briefly the activities and typical results up to FY2005 on powder alloy technology of advanced magnesium alloy to be used as structural materials.抄録全体を表示PDF形式でダウンロード (1395K)
研究
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村越 庸一, 初鹿野 寛一, 松崎 邦男2007 年 54 巻 9 号 p. 653-657
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスMagnesium chips less than 1 mm sizes, which are produced by the cutting of AZ91Ca2 alloy billet, are pressed at 423K and 573K to make a preform. The preforms are extruded at 623K on the extrusion ratio of 5 and 20. Microstructure of a test piece is observed by an optical microscope. Mechanical properties, fracture strength and strain, are also examined by compression test between room temperature and 523K. Microstructure shows dense microstructure with the increasing of pressing temperature and extrusion ratio. On the extrusion ratio of 5, the fracture strength and strain at the pressing temperature of 423K and 573K are 400MPa and 0.15 and 416MPa and 0.14 at the room temperature. The fracture strength and strain at the extrusion ratio of 20 are 370MPa and 0.39 at the room temperature. Influence of the pressing temperature on the fracture strength and strain is smaller than the influence of the extrusion ratio. Also the fracture strength is decreasing and the fracture strain is increasing with the increasing of the test temperature. Above the test temperature of 523K, remarkable fracture is not shown on the test pieces. From these results, recycled magnesium alloy show possibility to be use as for plastic forming materials.抄録全体を表示PDF形式でダウンロード (1076K) -
砂田 聡, 川村 貴人, 近藤 勝義, 能登谷 久公, 真島 一彦2007 年 54 巻 9 号 p. 658-664
発行日: 2007年
公開日: 2008/02/20
ジャーナル オープンアクセスThe fundamental corrosion behavior of conventional AZ-series Mg alloys, i.e. AZ31, AZ61 and AZ91, has been conducted through the electrochemical test to investigate the corrosion behavior of extruded Mg alloys using powders fabricated by roll compaction process (RCP). The corrosion behavior of AZ-series Mg alloys depended on the standard electrode potential of Al content in Mg alloys. And the corrosion resistance has been improved most in AZ91 Mg alloy. The corrosion behavior of extruded AZ31B Mg alloys using powders fabricated by RCP has been also investigated through the polarization test, immersion test and SEM observation in comparison to that of the conventional AZ31W Mg alloy. The extruded AZ31B Mg alloys using RCP powder showed little change in Ecorr irrespective of number of pass cycles. Both anodic and cathodic current density suppression of the RCP specimens became larger with an increase in number of pass cycles. It was also confirmed that the corrosion characteristics of the RCP specimens depended strongly on their structural morphology and that the corrosion resistance of the RCP specimens subjected to 50 pass cycles was nearly same as that of the I/M specimen.抄録全体を表示PDF形式でダウンロード (1446K)
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