• Title/Summary/Keyword: Bi-2223 tapes

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Over-critical current characteristics of a Bi-2223 tape (Bi-2223테이프의 과임계전류 특성)

  • 박권배;이성수;류경우;이지광;차귀수
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2000.02a
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    • pp.128-129
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    • 2000
  • The over-critical current behaviors for bare or insulated Bi-222 tapes with different matrix materials have been examined. The result shows that static resistances of the two bare tapes becomes similar for currents above 150 A but different for currents below. In the insulated A tape the first rapid temperature rise occurred around 180 A and eventually burned out about 190A.

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Magnetization Loss Characteristics of Bi-2223 Tapes in Longitudinal Magnetic Field (Bi-2223데이프의 종자계 손실 특성)

  • Kim, Hyun-Jun;Ryu, Kyung-Woo
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.851-853
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    • 2002
  • Bi-2223도체의 종자계 손실에 대하여 실험적으로 조사하였으며, Bi-2223도체의 종자계 손실은 주파수에는 의존하지 않으며, 이는 수직 수평방향의 자장에 대한 자화손실처럼 히스테리시스손실이 지배적임을 의미한다. 또한 측정된 자계 손실은 절충 본수에도 그다지 의존하지 않으며, 필라멘트들 사이가 완전히 비결합된 모델로부터 계산된 손실에 더 유사하고, 수평방향의 자장에 대한 자화손실의 약 1/5정도로 작으며, 따라서 종자계 손실은 전력기기에서 그다지 중요하지 않음을 알수 있었다.

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Fabrication and evaluation of microstructural evolution and critical property of twisted Bi-2223 superconductor tape (Twisting된 Bi-2223 선재의 제조, 미세조직 관찰 및 임계 특성평가)

  • 임준형;지봉기;박형상;주진호;장미혜;고태국;이상진;하홍수;오상수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.3
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    • pp.241-246
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    • 2000
  • We fabricated Bi-2223 multi-filaments superconductor tape and evaluated the effect of twisting on the microstructural evolution and critical current. Twist pitches of the tapes are in the range of 70- 8mm and uniformly deformed. It was observed that grain size and the degree of texture decreased as decreasing pitch probably due to the formation of the irregular interface between Ag and filaments. In addition critical current of the tapes decreased to 6.5 A with decreasing pitch to 8mm, showing 48% of degradation compared to the untwisted tapes decreased to 6.5 A with decreasing pitch to 8mm, showing 48% of degradation compared to the untwisted tape(12.5 A). These reduction of critical current may be related to the interface irregularity smaller grain size worse texture and the presence of cracks due to the induced strain during twisting processing.

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Study on crystal texture of PIT processed Bi-2223 multi-filamentary tape (PIT 공정으로 제조한 Bi-2223 다심 고온 초전도 선재의 결정 배향성에 관한 연구)

  • Choi, J.K.;Oh, S.S.;Ha, H.S.;Yang, J.S.;Yun, J.K.;Lee, N.J.;Ha, D.W.;Kwan, Y.K.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.04a
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    • pp.59-63
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    • 2002
  • The purpose of this paper is to investigate the crystal texture of the 2223 phase and its relationship with PIT processing parameter. Ag-sheathed Bi-2223 multi-filament tapes were prepared by changing rolling reduction ratio. We analysed the degree of texture for 2223 phase after heat-treatment. According to X-ray pole-figure, the texture of the filaments located near surface and center were not so different each other for all rolling conditions. we found a little higher degree of texture for 60% rolling reduction. But its difference is not so high compared with those tapes with a lower rolling reduction ratio. Reaction induced texturing seemed to contribute with a large portion under present condition.

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Fundamental Electro-Mechanical Characteristics of Ballooning-Resistant Bi-2223 HTS Tapes (벌루닝 손상에 강한 Bi-2223 테이프의 기본적인 전기-기계적 특성)

  • Dizon, John Ryan C;Shin, Hyung-Seop;Ha, Dong-Woo;Cho, Jeon-Wook;Oh, Sang-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.26-27
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    • 2006
  • The fundamental mechanical characteristics under tensile and bending deformations of hermetically-sealed reinforced Bi-2223 tape and CTOP processed Bi-2223 tape were examined at 77K. Also, the Tensile strain dependence of the critical current, $I_c$, was obtained at 77K and self-field. The reinforced hermetic tape showed higher tensile strength and a better Tensile strain tolerance than the CTOP processed tape. For bending tests, a rho-shaped sample holder was used giving multiple bending strains. in increasing order. In the same case under bending deformation, the hermetic tape showed a higher bending strain tolerance than the CTOP processed tape. This higher strength of the hermetic tape can be attributed to the thick hardened copper reinforcement layer.

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The effect of heat treatment condition on superconducting property and phase analysis of Bi-2223 tapes (Bi-2223 초전도 선재의 열처리에 따른 초전도 특성 및 상분석)

  • Choi, Jeong-Kyu;Ha, Hong-Soo;Lee, Dong-Hun;Yang, Ju-Saeng;Hwang, Sun-Yuk;Ha, Dong-Woo;Oh, Sang-Soo;Kwon, Yeong-Kil;Lee, Se-Jong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05a
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    • pp.73-76
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    • 2003
  • Phase transformation of Bi-2223 tape during the final heat treatment has been investigated through the various duration time of heat treatment in a specially designed 3-step heat treatment. It was found that the phase assemblage in the sintering was determined by the sintering time and temperature. In this study, sintering time was changed to optimize the Bi-2223 phase assemblage, and acquire high critical current density. High critical current samples with Ic = 85 A and Je = 8.9 kA/$cm^2$ have been measured at 77K and self-field for 55-filament tapes sintered by optimum condition.

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Characterizations of fine Bi-2223 precursor powder by spray pyrolysis process (분무 열분해법으로 제조된 미세 Bi-2223 전구분말의 특성)

  • Kim S. H.;Yoo J. M.;Ko J. W.;Kim Y. K.
    • Progress in Superconductivity
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    • v.6 no.2
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    • pp.124-128
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    • 2005
  • Homogeneous and fine powders for Bi-2223 tape were prepared by ultrasonic spray pyrolysis (SP) method from an aqueous solution of metal nitrates. Bi-2223 precursor powders were synthesized with various solutes concentration and pyrolysis temperature. The synthesized precursor powders had a narrow particle size distribution and an average particle size was $\~{\cal}um$. The reactivity of precursor powder by SP method is very high, attributed to the fine and narrow particle size distribution. Bi-2223/Ag tape was prepared using PIT method and followed by various sintering conditions. The precursor powder by SP method promoted a very quick formation of the Bi-2223 phase for short sintering time while the secondary phase such as large AEC phase and $Ca_2PbO_4$ were minimized for SP tapes.

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Development and fabrication of multi-filamentary Bi(2223)/Ag jointed tape (Bi(2223)/Ag 다심 초전도 접합선재의 제조)

  • 김규태;김정호;김호진;이동욱;주진호;나완수
    • Progress in Superconductivity
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    • v.4 no.2
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    • pp.172-175
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    • 2003
  • Critical current ratio and n-value of Bi(2223)/Ag superconducting joint tape were measured as a function of uniaxial pressure. In the superconducting joint method, MM and MSM joint were used ; MM joint is direct connection of two -multi filamentary tapes, and MSM is connection of them by using a single -filamentary tape. It was observed that the critical current ratio(CCR) for jointed tapes was not dependent on the uniaxial pressure but joining methods. The n-value of jointed tapes has similar trends with that of the CCR. Especially, double MSM joint showed the highest electrical properties as 63.4-76.0%(CCR) and 3.5-5.1 (n-value). It is considered that the improvements are due to the better inter connections of multifilaments by two single filamentary tapes on both sides.

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