• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.1-4
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• 2001

For the practical use of a superconducting wire to magnet application, it is important to assess the Young modulus and other mechanical properties of HTS tapes. In order to establish a test method of mechanical properties for oxide composite superconductors. tensile tests of Bi-2223 multi- filamentary tapes were carried out at room temperature, as an activity of the International round robin test proposed by the committee of VAMAS/TWA 16-Subrgroup. The tapes consisting of mutli-filamentary showed a three stage tensile behavior. At the initial stage of the stress-streain curve. The elastic deformation existed in a quite nattrow strain region. But the plastic deformation was observed in a wide strain region due to the platic flow of the Ag alloy matrix. The results of RRT were also reported and discussed.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.13-16
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• 2001

In the practical sense, it is important to assess the Young modulus and the degradation of $I_{c}$ due to mechanical deformation in HTS tapes for designing superconducting magnets. In order to establish a test method of mechanical properties in oxide composite superconductors, the committee of VAMAS/TWA 16-Subgroup proposed an international round robin test. The first effort has been focused on the multifilamentary Bi-2223 tapes. Eight groups participated in the RRT activity and each group carried out the tensile test by their own professional technique to three kinds of Bi-2223 tapes. The experimental details were reported and discussed for your information.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.69-72
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• 2004

In order to use HTS tape on electric power applications, such as cable, motor, transformer, fault current limiter, a long length of HTS tape with a good uniformity of critical current is inevitable. The longer length of HTS tape, the wider in the range of application and the lower cost of HTS tape. In this study three long length Bi-2223/Ag tapes(268m, 253m and 187m) were fabricated. Critical current uniformity along the length was greatly improved through the optimization of cold deformation and thermo-mechanical process. Average critical current of the tapes was 63.2 A, 54.6 A and 64.2 A, respectively Critical tensile strength and critical bending radius (77 K, 5 % Ic degradation) was 135 MPa and 56 m, respectively.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.236-240
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• 2000

Bi-2223 HTS current leads for a superconducting magnetic energy storage(SMES) magnet were designed and manufactured. The HTS leads composed of Bi-2223/AgAu tapes and stainless steel former were connected to conventional vapor-cooled copper leads. The heat input to the liquid helium through the HTS lead was 0.39 W/lead when the warm end part's temperature is 65 K. And, the critical current of the HTS leads was about 1.6 kA when the warm end part's temperature is 80 K. The measured those values are well consistent with computed values.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1489-1491
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• 1996

The effect of Ag alloy sheath have been investigated in terns of critical current density and mechanical property. Nevertheless the continuous improvement of critical current density($J_c$) of Ag sheathed Bi2223 oxide superconducting wire processed with powder in tube(PIT) method, poor mechanical strength is still considered to be demerits for power application. In this study, we prepared two kinds of Ag- x wt% Cu alloy and pure Ag sheathed Bi2223 superconducting tapes. The hardness and tensile strength of prepared tapes has been measured. Their mechanical propertes were improved by Ag alloying.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.198-201
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• 1996

In order to investigate control factors to critical current density, Ag sheathed Bi2223 superconducting tapes were fabricated using PIT process. Optimizing the reduction ratio of rolling, critical current density 7f rolled Bi2223 tape could be improved with the value of 15,000 A/$\textrm{cm}^2$(77 K, zero field). The correlation between J$\_$c/ and work inhomogeneity was revealed as a dependence of COV of measured oxide layer thickness.

• Progress in Superconductivity
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• v.3 no.2
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• pp.193-197
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• 2002

There are many problems in wire fabrication of long length Bi-2223 superconductor by using conventional extrusion method. They are mainly due to high surface resistance and inhomogeneous distribution of inner stress. Hydrostatic extrusion process will not only decrease the extrusion pressure but also enhance homogeneous deformation of material by reducing friction force between billet and container Hydrostatic extrusion method is considered to be useful fur fabrication of the homogeneous wire with high density. In this paper, hydrostatic extrusion process is introduced to fabricate Bi-2223 superconducting tape, and also discussed are the interface homogeneity and microstructural aspects of extruded BSCCO/Ag billet.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.257-260
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• 2003

Bi-2223 tape is one of the most widely used HTS tapes for power application. This paper presents the basic properties such as temperature and resistivity rise of the Bi-2223 tape which is exposed to the over current. Temperature and resistivity were measured by E-type thermocouple and voltage taps. Results of the measurement showed that rise of voltage depended on the magnitude of the over current until several times of the rated current. When the current largely exceeded the rated current, rise of voltage depended on the magnitude of the resistivity of the Ag matrix because temperature of the matrix increased to a great extend.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.488-491
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• 2000

Bi-2223/Ag superconducting wires have been mainly prepared by a powder-in-tube method. The drawing and the rolling are main processes to increase the core density and wire length. In the fabrication of long wire, especially, the drawing should be precisely controlled to assure the filament homogeneity. In this paper, the influences of drawing die angle, bearing length and reduction ratio on the sausaging and the critical current density of the wire are investigated. Single cored and multi-filamentary wires are fabricated by PIT method with different conditions. The core densities and sausaging in the wires are investigated and are discussed regarding their relationship to the I$_{c}$. It was made clear that the geometry of drawing die is sensitively dependent on the sausaging. The improvement of I$_{c}$ was achieved by reducing the die angle and high core density.ity.