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-Tc superconducting tapes and wires. A normal-metal sheet coated with high-Tc 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 oxygénation in optimizing Tc and Jc has been studied. Preliminary results indicate that partialmelt texturing, in the Bi2Sr2CaCu2O8 Ag system, results in a relatively field independent Jc (H ≲ 7T) with Jc(H = 0) ~ 5 × 104 A cm-2 at 4.2 K. © 1992.