Fabrication and performance of long (BixPb1-x)(2)Sr2Ca2Cu3O delta/Ag composite tapes

Recent advances in the development of Bi-2223/Ag composite tapes are reviewed. Monofilamentary, 7- and 19-filament tapes were produced by the powder-in-tube route. Control of the mechanical deformation showed that regular filament shapes could be obtained, both transversally and longitudinally. A kinetics study on the ceramic-silver interface of monofilaments confirmed that the conversion of the precursor into Bi-2223 was a two-dimensional process. Critical current densities and the n exponent of tapes decreased with increasing length, and both effects could be partly ascribed to a larger defect density in long tapes. For 100 m long tapes, the critical currents of 10 m sections were within 8% of the mean value. Measured a.c. losses were found to correspond to a geometry intermediate between an ellipse and a thin strip. (C) 1997 Published by Elsevier Science Ltd.