Yb. Huang et al., Enhancing the engineering J(c) of Bi-2223 multifilamentary tapes by two-axial rolling and periodic pressing, IEEE APPL S, 9(2), 1999, pp. 2722-2725
Bi-2223 multifilamentary tapes with a filling factor from 20 to 51% have be
en produced by a modified Powder-In-Tube method, where a tffo-axial rolling
method is used to replace the standard drawing process. Because the two-ax
ial rolling process does not apply tensile force during wire fabrication an
d every filament receives a very similar reduction during the deformation p
rocessing of the wire into a tape, the size homogeneity of filaments can be
significantly improved for tapes with high filling factor. Combining this
with a periodic pressing process, the engineering critical current density
has been increased from 4 to 8 kA/cm(2) (77 K, 0 T) for tapes with a fillin
g factor of 35%. The effect of deformation and heat-treatment conditions on
the microstructure and transport properties has been found to be quite dif
ferent in tapes with high filling factor.