Near-net-shape fabrication of continuous Ag-clad Bi-based superconductors

We have developed a near-net-shape process for Ag-clad Bi-2212 superconduct ors. This alternative to the powder-in-tube process offers the advantages o f nearly continuous processing, minimization of processing steps, reasonabl e ability to control the Bi-2212/Ag ratio, and early development of favorab le texture of the Bi-2212 grains. The powder is rolled into an Ag channel, a cap is applied, and the assembly is lightly rolled. To minimize distortio n during heat treatment, it is especially important that the Bi-2212 powder be nearly free of volatile species such as carbon. A vacuum-calcination pr ocess was developed to control CO2 evolution during heating. Superconductin g properties are discussed.