• Title/Summary/Keyword: Bi-2223/Ag superconducting tape

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Evaluation of mechanical properties of Bi-2223/Ag HTS tapes (Bi-2223/Ag 고온초전도 선재의 기계적 특성 평가)

  • 하홍수;이동훈;양주생;최정규;윤진국;하동우;오상수;권영길
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.351-354
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    • 2002
  • In most of electrical applications using Bi-2223/Ag HTS tapes, bending and tension stresses are essentially applied to the tape. Therefore, the critical current of the Bi-2223/Ag tape is degraded by increasing the deformation stress, though brittle superconducting filaments are embedded in the reinforced Ag alloy sheath. It is needed to understand bending and tension properties of HTS tapes at room temperature and cryogen to make superconducting magnet, cable and etc. using Bi-2223/Ag HTS tapes. Actually, bending and tension stress applied to the tapes simultaneously, when winding the tapes on former for applications. In this study, the effect of mechanical deformations, bending and tension, on the critical current of Bi-2223/Ag tape was investigated.

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Study on commercialization process of Bi-B223 HTS tape (Bi-2223 고온초전도 선의 상용화 공정 연구)

  • 하동우;김상철;오상수;하홍수;이동훈;양주생;황선역
    • Progress in Superconductivity and Cryogenics
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    • v.6 no.1
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    • pp.1-5
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    • 2004
  • Long length of Bi-2223/Ag superconducting wives were fabricated by stacking and drawing process with advanced heat-treatment schedules. Intermediate annealing was carried out to increase the homogeneity and uniformity of the superconducting filaments embedded in the silver matrix. Phase modification from tetragonal to orthorhombic Bi-2212 by pre heat treatment(PHT) was executed to improve the texture and phase transformation of Bi-2223. Drawing stress was measured to predict the sausaging and stress limit. Rolling Parameters such as thickness. width and winding tension were investigated to roll the tape with uniformity. 1 km length of Bi-2223/Ag superconducting wires were fabricated without any breakage. Critical current (Je) of 270 m length of superconducting tapes was measured over than $70 A/cm^2$ continuously after final sintering.

Critical Current Properties of Bi-2223/Ag tapes with respect to axial Strain (Bi-2223/Ag 고온 초전도 선재 변형에 따른 입계전류 특성)

  • 하홍수;오상수;하동우;심기덕;김상철;장현만;권영길;류강식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.1
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    • pp.69-73
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    • 2001
  • In this study, we fabricated Bi-2223/Ag high temperature superconducting tapes using PIT(Powder-In-Tube) process to apply the superconducting magnet, cable and etc. It is inevitable to deform the superconducting taps with axial strain for application. Therefore, for the characterization of the strain sensitivity of the superconducting properties, the degradation of Bi-2223/Ag tapes due to axial strain were investigated by measuring the critical current as a function of applied tension strain and external magnetic field. The critical current of Bi-2223/Ag tapes were decreased slightly up to 0.3∼0.4% applied strain but, drastically decreased more than these strains. Superconducting filament cores consisted of brittle ceramic fibers were broken easily by the large strain and current path were decreased simultaneously.

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Critical Current Properties of Bi-2223/Ag tapes with respect to axial Strain (Bi-2223/Ag 고온초전도 선재의 변형에 따른 임계전류 특성)

  • 하홍수;오상수;하동우;심기덕;김상철;배성우;권영길;류강식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.810-813
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    • 2000
  • In this study, we fabricated Bi-2223/Ag high temperature superconducting tapes using PIT (Powder-In-Tube) process to apply the superconducting magnet, cable and etc. It's inevitable to deform the superconducting tapes with axial strain for application. Therefore, for the characterization of the strain sensitivity of the superconducting properties, the degradation of Bi-2223/Ag tapes due to axial strain were investigated by measuring the critical current as a function of applied tension strain and external magnetic field. The critical current of Bi-2223/Ag tapes were decreased slightly up to 0.3∼0.4% applied strain but, drastically decreased more than these strains. Superconducting filament cores consisted of brittle ceramic fibers were broken easily by the large strain and current path were decreased simultaneously.

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The effects of moisture content in precursor powder for Bi-2223/Ag tape (Bi-2223/Ag 선재의 전구 분말에서 수분함량에 따른 효과)

  • 김성환;유재무;고재웅;김영국;김철진
    • Progress in Superconductivity
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    • v.4 no.2
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    • pp.162-167
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    • 2003
  • The critical current value of Bi-2223/Ag tape can be influenced by various factors. In particular, it was known that properties of precursor powders could affect the formation of Bi -2223 and grain growth rate of the same. Since, moistures and organic matters can easily contaminate the precursor powders of Bi-2223 tapes and degrade properties of superconductors, the precursor powders should be kept in optimal conditions to minimize contamination. In this study, the effect of moisture and organic matters has been investigated. A Bi-2223/Ag tape contaminated with a large amount of moisture and organic matter has been characterized by low critical current values and bubbling. It has been found that as the quantity of moisture increases, the Bi-2223 phases are formed at lower temperature and the amount of non-superconducting phase increases.

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Properties of Bi-2223/Ag HTS tapes using different content of precursors (조성이 다른 전구체 분말에 따른 Bi-2223/Ag 초전도 테이프의 특성 변화)

  • Ha, Dong-Woo;Yang, Joo-Saeng;Ha, Hong-Soo;Oh, Sang-Soo;Hwang, Sun-Yuk;Lee, Dong-Hoon;Choi, Jung-Kyu;Lee, En-Yong;Kwon, Young-Kil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05a
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    • pp.69-72
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    • 2003
  • Bi-2223 superconducting wires were fabricated by stacking, drawing process with different precursor powders and different heat-treatment histories. The precursor powders were 2 kinds of Pb content. And a part of the tapes were experienced pre-annealing process which caused tetragonal structure of Bi-2212 phase to orthorhombic structure of it was during drawing process. We confirmed the transformation of Bi-2212 phase from tetragonal structure to orthorhombic structure and reduction of second phases. XRD and DC magnetization analysis were performed in order to investigate the fraction of Bi-2223 phase in Bi-2223/Ag HTS tape. We could achieve best Ic of 70 A class at the Bi-2223/Ag tape using low Pb content of precursor powder and experienced pre-annealing process. DC magnetization analysis was useful to investigate the fraction of Bi-2223 phase in the Bi-2223/Ag tape.

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Properties of Bi-2223/Ag HTS tapes prepared using powders of varying lead content (Pb 함량을 달리한 전구체 분말에서의 Bi-2223/Ag 초전도 테이프의 특성 변화)

  • Ha, Dong-Woo;Yang, Joo-Saeng;Hwang, Sun-Yuk;Ha, Hong-Soo;Oh, Sang-Soo;Lee, En-Yong;Kwon, Young-Kil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.585-588
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    • 2003
  • Bi-2223 superconducting wires were fabricated by stacking, drawing process with different precursor powders and different heat-treatment histories. The precursor powders were 2 kinds of Pb content. And a part of the tapes were experienced pre-annealing process which caused tetragonal structure of Bi-2212 phase to orthorhombic structure of it was during drawing process. We confirmed the transformation of Bi-2212 phase from tetragonal structure to orthorhombic structure and reduction of second phases. AC magnetization analysis were performed in order to investigate the fraction of Bi-2223 phase in Bi-2223/Ag HTS tape. The cross sections of 55 filaments and 61 filaments were investigated after rolled in order to understand deformation mechanism of superconducting cores. We could achieve best Ic of 70 A class at the Bi-2223/Ag tape using low Pb content of precursor powder and experienced pre-annealing process. AC magnetization analysis was useful to investigate the fraction of Bi-2223 phase in the Bi-2223/Ag tape.

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The Effect of Deformation Stress-strain and Temperature on the $I_c$ Degradation of Bi-2223/Ag Tapes

  • Ha, Hong-Soo;Kim, Sang-Cheol;Ha, Dong-Woo;Oh, Sang-Soo;Joo, Jin-Ho
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1251-1252
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    • 2006
  • In order to investigate 95% retained critical current of Bi-2223/Ag tapes under various stress-strain conditions, load cell attached tension and bending apparatus was used. The critical current of stress-strained tape was degraded below 95% retained critical current when tension and bending was simultaneously applied together. But only one of this tension or bending did not degrade the tape below 95% retained critical current. Deformation temperature was important to maintain the 95% retained Ic of Bi-2223/Ag tapes after bending or tension deformation because mechanical strength of tapes can be changed drastically between room temperature and 77 K.

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Mechanical properties at Bi-2223 HTS tapes with various sheath materials (기지금속을 달리한 Bi-2223 초전도 선에서의 기계적 특성 변화)

  • Ha, Dong-Woo;Lee, Dong-Hoon;Yang, Joo-Sang;Kim, Sang-Chul;Hwang, Sun-Yuk;Ha, Hong-Soo;Oh, Sang-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.551-554
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    • 2004
  • Bi-2223 HTS tapes are used widely for application of superconducting power systems. However there are need the properties of high strength and low AC loss. Two kinds of Bi-2223 HTS tapes with different Ag sheath were used to know the effect of sheath alloying for the strength and the resistivity. The workability and reaction degree of superconducting phase at Bi-2223 HTS tapes were investigated. We designed conventional type-Ag/alloy and double sheathed mono filament type-Ag/alloy/alloy in order to increase the strength and resistivity of matrix in Bi-2223 HTS tapes. The effect of axial strain and thermal cycling on the critical current was investigated for the Bi-2223 HTS tapes. Because the workability of double sheath Bi-2223 HTS tape was lower than one sheath Bi-2223 HTS tape, it was need additional softening treatment. Bi-2223 formation reaction was decreased by Ag alloy matrix during sintering process. Two kinds of Bi-2223/Ag tapes with different Ag sheath were used to know the effect of sheath alloying for the tensile strain. Critical current is drastically decreased for Ag/alloy and Ag/alloy/alloy sheathed tapes at tensile strain above 0.24 % and 0.34 %, respectively. This result showed that mechanical strength was increased over than 40 % by introduce double sheath at mono filament stage.

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