• 제목/요약/키워드: superconductivity

검색결과 3,305건 처리시간 0.033초

Effect of pre-annealing conditions on critical current density of Bi-2223 tapes

  • Ha, Dong-Woo;Yang, Joo-Saeng;Ha, Hong-Soo;Oh, Sang-Soo;Lee, Dong-Hoon;Hwang, Sun-Yuk;Park, Jung-Gyu;Kwon, Young-Kil
    • 한국초전도ㆍ저온공학회논문지
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    • 제5권1호
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    • pp.31-34
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    • 2003

  • Bi-2223 superconducting wires with 55 filaments were fabricated by stacking, drawing process with different heat-treatment histories. Two kinds of powders were prepared. One was pre-annealed at 760-820 $^{\circ}C$ and low oxygen partial pressure, and the other was only calcined state. Before rolling process, round wires were pre-annealed at 760 -820 $^{\circ}C$ and in a low oxygen partial pressure. We confirmed that pre-annealing step was to transform Bi-2212 orthorhombic structure from Bi-2212 tetragonal structure and to reduce the formation of second phases at superconducting wire. However Bi-2223 phases were formed at higher pre-annealing temperature. Bi-2223 conductor was needed frequently annealing at low temperature because pre-annealing at precursor powder brought about decrease in workability. We could achieve highest Je of 6500 A/$\textrm{cm}^2$ at the tape using Bi-2212 orthorhombic phase by introduced slightly overheating at the 1st sintering process.

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