DocumentCode :
1548800
Title :
Influence of rolling pressure on microstructures and current path evolution in Ag-sheathed Bi2223 monocore tapes
Author :
Oota, A. ; Kawano, K.
Author_Institution :
Toyohashi Univ. of Technol., Japan
Volume :
9
Issue :
2
fYear :
1999
fDate :
6/1/1999 12:00:00 AM
Firstpage :
2529
Lastpage :
2532
Abstract :
The influence of rolling pressure on microstructures and current transports has been investigated on Ag-sheathed Bi2223 monocore tapes, fabricated by a rolling process while changing mechanical load (i.e., rolling pressure). In combination with metallurgical studies, analyses on trapped-magnetic fields in a remanent state by a scanning Hall sensor show the evolution in transport current paths in the superconductor core, and also reveal critical current distributions therein. Enhancement of transport critical current density J/sub c/ at 77 K and 0 T with an increase in rolling pressure P up to /spl sim/0.3 GPa is ascribed to the evolution in transport current paths due to strengthening grain connectivity. Degradation in J/sub c/ with a further increase in P exceeding 0.3 GPa is caused by the occurrence of a sausaging effect. An optimum value of P is determined by a competition between strengthening grain connectivity and the occurrence of the sausaging effect. Numerical calculations on magnetic profiles give a variation of current capacity along a width direction in the core, so the local J/sub c/ value at the edge is 4-5 times greater than the value at the center.
Keywords :
bismuth compounds; calcium compounds; ceramics; composite superconductors; critical current density (superconductivity); crystal microstructure; high-temperature superconductors; magnetic field effects; materials preparation; remanence; rolling; silver; strontium compounds; superconducting tapes; 0 T; 77 K; Ag-Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O; Ag-sheathed Bi2223 monocore tapes; current path evolution; grain connectivity strengthening; magnetic profiles; metallurgical studies; microstructures; remanent state; rolling pressure influence; scanning Hall sensor; transport critical current density J/sub c/; trapped-magnetic fields; Ceramics; Critical current; Critical current density; Magnetic field measurement; Mechanical sensors; Microstructure; Pressure measurement; Scanning electron microscopy; Superconducting films; Surface morphology;
fLanguage :
English
Journal_Title :
Applied Superconductivity, IEEE Transactions on
Publisher :
ieee
ISSN :
1051-8223
Type :
jour
DOI :
10.1109/77.785001
Filename :
785001
Link To Document :
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