Superconductor technology: apparatus – material – process – High temperature devices – systems – apparatus – com- ponents,... – Electrical energy storage device – inductor – transformer,...
Patent
1990-11-29
1994-05-17
Picard, Leo P.
Superconductor technology: apparatus, material, process
High temperature devices, systems, apparatus, com- ponents,...
Electrical energy storage device , inductor, transformer,...
1741251, 335216, 505700, 505704, 505705, 505230, H01F 722, H01B 1202
Patent
active
053128028
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to oxide superconductive wires, a method of manufacturing oxide superconductive wires and products using the oxide superconductive wires. More specifically, the present invention relates to an improvement for preventing, when an oxide superconductive wire is bent, degradation of superconductivity caused by the bending.
BACKGROUND ART
Metal superconductors, compound superconductors and oxide superconductors have been known and various applications thereof have been studied. A superconductor has its electrical resistance made zero when it is maintained at a temperature not higher than a critical temperature. Generation of high magnetic field, high density transfer of large current and so on have been tried utilizing this characteristic.
Recently, attention is beginning to center on oxide superconductive materials, which have higher critical temperature at which the superconductive phenomenon occurs. Such superconductive materials can be used for power transmission and distribution, electrical connection between various equipment and elements, AC coils and so on, when they are turned into longitudinal wire bodies.
Various methods have been known to fabricate wires of oxide superconductive materials. In one method, powder of oxide superconductive material is filled in a metal pipe and the cross section thereof is reduced. In another, a layer of oxide superconductive material is formed on a longitudinal base. Gas phase thin film deposition such as vapor deposition, sputtering and CVD may be applied as a method of forming the oxide superconductive layer.
Generally, oxide superconductive materials are weak on strain, especially tensile strain, and when a tensile strain is generated, for example, superconductivity such as critical temperature and current density is significantly degraded. When a longitudinal oxide superconductive wire is bent, a tensile strain is generated in some portion or other inevitably. In order to lengthen the oxide superconductor while suppressing generation of strain such as the tensile strain as much as possible, a method of forming a thin oxide superconductive layer on a fiber-type or film-type thin or narrow flexible base has been known. By this method, the wire can be bent to be have smaller diameter with the same allowable strain.
However, there is a limit in the above described method, and oxide superconductive wires which are stronger against strain have been desired for practical use.
Therefore, an object of the present invention is to provide oxide superconductive wires which are stronger against strains.
Another object of the present invention is to provide a method of manufacturing the above described oxide superconductive wires which are stronger against strains.
A further object of the present invention is to provide products using the above described oxide superconductive wires.
DISCLOSURE OF THE INVENTION
The inventors of the present invention have found that the oxide superconductor is weak on tensile strain but relatively strong against compressive strain, and the inventors have attained the present invention based on this finding.
The oxide superconductive wire in accordance with the present invention has an oxide superconductive layer formed on a longitudinal flexible base, wherein the compressive strain is remained in the oxide superconductive layer in the longitudinal direction to solve the above described technical problem.
The base used in the present invention is, typically, a tape-type or fiber-type base.
Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O, Bi-Pb-Sr-Ca-Cu-O, Tl-Ba-Ca-Cu-O, Tl-Pb-Ba-Ca-Cu-O and other materials are used as the oxide superconductive materials for forming the oxide superconductive layer in the present invention. Any of these materials exhibits superconductivity by heat treatment at 400.degree. to 1000.degree. C. In the present invention, the above mentioned step of heat treatment and a succeeding step of cooling can be advantageously used to provide preliminary strain of compression on the oxide superconducti
REFERENCES:
patent: 5168127 (1992-12-01), Kohno et al.
T. Konaka et al.: "Preparation of Y-Ba-Cu-O Superconducting Tape by Atmospheric Plasma Spraying", Japanese Journal of Applied Physics Letters vol. 27, No. 6, Jun. 1988, Tokyo, JP pp. 1092-1093.
Patent Abstracts of Japan vol. 13, No. 99 (E-724) Mar. 8, 1989 & JP-A-63 274017.
IBM Technical Disclosure Bulletin "Superconducting ceramic-metal structure" vol. 32, No. 4B, Sep. 1989, New York, US pp. 85-86.
Patent Abstracts of Japan vol. 13, No. 254 (E-772) Jun. 13, 1989 & JP-A-1052327.
Hayashi Noriki
Hitotsuyanagi Hajime
Okuda Shigeru
Takano Satoshi
Barrera R.
Picard Leo P.
Sumitomo Electric Industries Ltd.
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