• Title/Summary/Keyword: Bi-2223/Ag tapes

Search Result 116, Processing Time 0.027 seconds

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
    • /
    • 2002.02a
    • /
    • pp.351-354
    • /
    • 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.

  • PDF

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
    • /
    • 2004.07a
    • /
    • pp.551-554
    • /
    • 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.

  • PDF

superconducting properties of Bi-2223 tapes with various heat treatment condition (열처리 온도 및 분위기 변화에 따른 Bi-2223 초전도 선재에서의 특성변화)

  • 하동우;이동훈;하홍수;오상수;김홍대;양주생;윤진국;최정규;권영길
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2002.07a
    • /
    • pp.527-530
    • /
    • 2002
  • A lot of efforts have been focused on the optimization of PIT parameters for Bi-2223/Ag wire. In this paper, initial annealing of Bi-2223/Ag wire to transform Bi-2212 orthorhombic from Bi-2212 tetragonal Precursor was investigated. This initial annealing step at low oxygen partial pressure were to transform Bi-2212 orthorhombic structure and to reduce the formation of second phases at superconducting wire. However Bi-2223 Phases were appeared at higher annealing temperature. Critical currents(Je) of Bi-2223/Ag tapes were sintered at low oxygen Partial pressure were higher than that of the wires sintered at atmosphere condition. In order to investigate the effect of rolling reduction ratio, Bi-2223/Ag HTS tapes were rolled with different reduction ratio. There were no clear difference of Je and filaments shape with various rolling reduction ratio.

  • PDF

The effect of heat treatment mass flow on superconducting property of Bi-2223/Ag Tapes. (열처리 가스유량에 따른 Bi-2223/Ag 초전도 테이프의 특성에 미치는 영향)

  • 양주생;하동우;이동훈;최정규;황선역;오상수;김상철;김명호
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
    • /
    • 2003.10a
    • /
    • pp.96-98
    • /
    • 2003
  • Many of research efforts have been focused on the improvement of critical current density Jc of silver-sheathed Bi-2223 tapes for practical applications of material. Bi-2223 superconducting wires with 55 filaments were fabricated by stacking, drawing process with different heat-treatment histories. After rolling process, Bi-2223 tapes were heat-treatment at 780~826$^{\circ}C$ with variable mass flow rate of mixed gas. In this study, the effect of changes in the variable mass flow rate of mixed gas during the heat treatment of Bi-2223/Ag tapes has been investigated. Distinct differences were observed in the Bi-2223 phase and critical current as flow rate of mixed gas. We could achieve proper conditions of mass flow rate of mixed gas for Ag-alloy clad Bi-2223 superconducting tapes.

  • PDF

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;김상철
    • Progress in Superconductivity and Cryogenics
    • /
    • v.4 no.1
    • /
    • pp.45-59
    • /
    • 2002
  • Evaluation of the mechanical properties of Bi-2223/Ag HTS tapes was carried out by the tension and bending tests. Most of the Bi-2223/Ag tapes retained critical current up to 10 kgf/mm$_2$ axial tension stress, and 0.2% tension strain at room temperature. Applied tension strain exceeding 0.3% in superconducting tapes at 77 K leaded to rapid degradation of the critical current. It was observed that the more filaments, the better axial tension property at 77 K, self-field The influence of bending strain on critical current degradation was revealed to be less sensitive for Bi-2223/Ag HTS tapes with a more number of filaments and higher silver ratio.

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
    • /
    • 2000.07a
    • /
    • pp.810-813
    • /
    • 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.

  • PDF

A study on the safe operation condition for Bi-2223/Ag tapes with applied alternating currents (교류용 Bi-2223/Ag 선재의 안정 통전 조건에 관한 연구)

  • Yim S. W.;Sohn S. H.;Hwang S. D.;Lim S. H.
    • Progress in Superconductivity
    • /
    • v.6 no.2
    • /
    • pp.138-141
    • /
    • 2005
  • Bi-2223/Ag tapes need to be safe, even it is under the over-critical current state for the protection of a superconducting power machine. However, it is not easy to identify the condition for the safe operation because of their broad S/N transition region. In this paper, for the study of the operation condition of Bi-2223/ Ag tapes, we investigated the V-I curves and the temperature variation of Bi-2223/ Ag tapes experimentally, applying alternating over-currents, and analyzed the relationship between resistance and temperature increase. For the experiments, a Bi-2223/Ag tape of 57 A $I_c$ was prepared, and the over-critical current characteristics under adiabatic state from $LN_2$ was measured. From the experiments, we confirmed that the Joule heating predicted by V-I curve corresponded with the increase of the measured temperature exactly. Using the results, a safe operation condition of Bi-2223 tape was discussed.

  • PDF

The effect of pre-treatment on superconducting property and deformation of Bi-2223/Ag tapes. (Bi-2223/Ag 고온초전도 선재의 전처리에 따른 가공성 및 초전도 특성)

  • Ha, Hong-Soo;Lee, Dong-Hoon;Choi, Jung-Kyu;Hwang, Sun-Yuk;Yang, Joo-Saeng;Kim, Sang-Chul;Ha, Dong-Woo;Oh, Sang-Soo;Kwon, Young-Kil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2003.05a
    • /
    • pp.25-29
    • /
    • 2003
  • Pre-treatment of Bi-2223/Ag tapes has been investigated to improve the superconducting property and grain alignment. However, rolling deformability of Bi-2223/Ag wires was degraded by the breakage of Ag alloy sheath after pre-treatment. Various pre-treatment conditions were tried to prevent the problem of sliver sheath and improve the superconducting property of Bi-2223/Ag tapes. Filament precursor of Bi-2223/Ag tapes was modified to be textured easily during main sintering by the optimum pre-treatment with low oxygen pressure and up to $800^{\circ}C$. Critical current was also increased up to 20% than that of no pre-treated tape.

  • PDF

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
    • /
    • v.14 no.1
    • /
    • pp.69-73
    • /
    • 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.

  • PDF

The effect of mechanical working on processing the Bi-2223/Ag tapes using PIT method

  • Oh, S.S.;Ha, D.W.;Kim, S.C.;Bae, S.W.;Kwon, Y.K.;Ryu, K.S.;Ha, H.S.
    • 한국초전도학회:학술대회논문집
    • /
    • v.10
    • /
    • pp.276-279
    • /
    • 2000
  • When high temperature superconducting tapes is fabricated using the PIT (Powder In Tube) method, the length of HTS tapes is increased more than 500 ${\sim}$ 1,000 times of initial powder packed billet. On mechanical processing, heterogeneous properties between the ceramic superconducting core and Ag/Ag alloy sheath occur the non-uniformity deformation as like sausaging that deteriorate the critical current properties of HTS tapes. In this study, we investigated the workability of Bi-2223/Ag/Ag alloy sheath tapes fabricated by the PIT method involving a number of different mechanical processes, multi drawing and rolling. In order to obtain the high critical current density and high uniformity of Bi-2223/Ag sheath tapes, the influences of powder packing density, drawing die angle and rolling parameters were studied. We found that the roll diameter is an important variable in the rolling process, as critical current of tapes rolled using 250 mm rolls was higher than that using 150 mm rolls.

  • PDF