並列タイトル等Casting of new superconducting composite materials
タイトル（掲載誌）宇宙開発事業団技術報告 = NASDA Technical Memorandum
一般注記スペースシャトルでの微小重力環境を利用して、合金が偏晶、共晶反応によって組織を形成するときの重力の影響を調べた。偏晶反応の対象として、Al-Pb-Bi系合金を、また、共晶反応にはAg-Yb-Ba-Cu系、ならびにAg-Cu系を選択し、加えて比較のためにAg-Y-Ba-Cu系の計4種類の系の溶融凝固を行った。フライト終了後、得られた試料の微細組織を観察し、加工または酸化熱処理後超電導特性の評価を行った。Al-Pb-Bi系ではAl母相中の(Pb,Bi)粒子の分布を調べた。微小重力下での試料では、(Pb,Bi)粒子が均一に分布しているのに対して、地上での試料では(Pb,Bi)粒子が重力方向に沈降しているのが観察された。得られた試料を線材に加工してその超電導特性を調べたところ、線材内の(Pb,Bi)繊維の近接効果により絶対温度9度K付近でその抵抗値がゼロになるのが観測された。また、Ag-Yb-Ba-Cu、Ag-Cu系共晶合金では、地上と微小重力下での試料それぞれの層状組織を比較したところ、地上試料では層間隔が小さく、試料全体にわたって均質な組織を有していたが、微小重力下での試料の組織は荒く、その右端と左端では組織が異なっていた。Ag-Ln-Ba-Cuについては観察後、合金を酸化熱処理し、得られたLn-Ba-Cu-O/Ag複合超電導体の特性を調べた。臨界温度に関しては微小重力下、地上で得られた試料共に低温で電気抵抗ゼロを示し、その臨界温度は70度K前後、遷移幅は20度K程度であった。4.2度K、0Tで臨界電流密度を調べたところ、いずれの試料もおよそ7A/平方ミリメートルで重力の影響はほとんど見られなかった。
Effect of gravity on the formation of composite structure by monotectic and eutectic solidification reaction was investigated utilizing microgravity in space shuttle. Selecting Al-Pb-Bi alloy as object of monotectic alloy, Ag-Yb-Ba-Cu alloy and Ag-Cu alloy as object of eutectic alloy, and Ag-Y-Ba-Cu alloy for comparison, melting and solidification test was performed. After the flight, microstructure of obtained samples was observed, together with after working or oxidation heat treatment, superconducting characteristics were evaluated. Distribution of (Pb, Bi) particles in Al mother phase was observed on Al-Pb-Bi system. It was found out that (Pb, Bi) particles were uniformly distributed in samples produced under microgravity, while (Pb, Bi) particles were deposited to direction of gravity in samples produced at ground surface. After obtained samples were fabricated to wire, superconducting characteristics of these wire were studied. It was observed from this experiment that electric resistance of these wire became zero near 9 K due to proximity effect of (Pb, Bi) fiber in wire. Comparison of lamellar structures of samples produced under ground surface and microgravity on Ag-Yb-Ba-Cu and Ag-Cu eutectic alloy indicated that lamellar gap in ground surface treatment sample was small and the structure was homogeneous over the sample, while the structure of sample produced under microgravity was rough and right side structure differed from left side. After above observation, oxidation heat treatment was given to Ag-Ln-Ba-Cu alloy and characteristics of obtained Ln-Ba-Cu-O/Ag complex superconductor were investigated. Electric resistance measured in relation to critical temperature became zero in ultra low temperature for both samples produced under microgravity and ground surface environment. Moreover, it was made clear that their critical temperature was about 70 K and transition width was approximately 20 K. Further, critical current density measured in 4.2 K, OT indicated about 7 A/sq mm for all samples and effects of gravity were not observed.
資料番号: AA0004116004
レポート番号: NASDA-TMR-940002 V.2
連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）
提供元機関・データベース宇宙航空研究開発機構 : 宇宙航空研究開発機構リポジトリ