Multifilamentary Bi-2223 composite tapes made by a metallic precursor route

Abstract

A process based on metallic precursors has been developed for manufacturing high filament count oxide superconductor-silver composite tapes with critical current densities of up to 7.5 kA/cm/sup 2/ at 77 K in zero field. A 30-cm prototype multistrand conductor made of these tapes has a critical current of 240 A at 77 K over a 9 cm gauge length, with an average critical current density of 6 kA/cm/sup 2/. The mechanical properties of tapes made from metallic precursors containing up to 10000 Bi-2223 superconducting oxide filaments were investigated. Critical tensile strains average 0.6%, and bend tests show negligible dropoff in current density up to a 0.70% surface strain. The critical current decrease beyond the 0.70% surface bend strain follows a simple model based on extensive filament damage beyond the critical tensile strain. Increased flow stresses of the composite tapes, compared to similarly processed silver, indicate considerable strengthening of the composite by the oxide filaments.<>