A JELLY-ROLL PROCESS FOR HIGH-TEMPERATURE SUPERCONDUCTING TAPES AND WIRES

As an alternative to the powder-in-tube method, a new technique called the jelly-roll process is proposed for making high-T(c) superconducting tapes and wires. A normal-metal sheet coated with high-T(c) cuprate is configured in a jelly-roll fashion and cold worked into tapes or wires made of alternating cuprate superconductor and normal metal layers. The feasibility of this new process is demonstrated for both the YBa2Cu3O7/Ag and Bi2Sr2CaCu2O8/Ag composite systems. The role of reduction in the cross-sectional area by cold-rolling, heat treatment and oxygenation in optimizing T(c) and J(c) has been studied. Preliminary results indicate that partial-melt texturing, in the Bi2Sr2CaCu2O8/Ag system, results in a relatively field independent J(c) (H less than or similar to 7T) with J(c)(H=0) is similar to 5X10(4) A cm-2 at 4.2 K.