Improved J/sub c/ of multifilamentary Bi,Pb(2223)/Ag tapes by periodic pressing

Critical current densities of multifilamentary Ag-sheathed Bi(2223) tapes up to about 35 000 A/cm/sup 2/ have been achieved at 77 K and self field for lengths of several meters using an improved route: periodic pressing. This corresponds to an increase by 30-40% compared to the values obtained for conventionally rolled tapes starting from the same powders. Several pressing steps have been introduced during the anneal instead of the only standard rolling step (based on previous studies performed on both mono- and multifilamentary tapes). In contrast to earlier attempts by pressing techniques, periodic pressing is a practical and scaleable process for the fabrication of long lengths of Bi(2223) conductor as the standard intermediate rolling step. Engineering critical current densities of 8 000 A/cm/sup 2/ have successfully been obtained for tapes with high filling factor (35%).