Improving both superconducting and mechanical properties of Bi-2223 bulk by composing with Ag wires

Abstract

(Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) superconductor is suitable to be applied under low field and near liquid nitrogen temperature. However, Jc value of Bi-2223 bulk material is much smaller than that of the wire and tape conductors. We prepared Bi-2223/Ag wires composite bulk to improve simultaneously both the superconducting and the mechanical properties. When twenty-four Ag wires of 0.4 mm in diameter were composed, the Jc value of the composite bulk was estimated to 1200 A/cm2 at 4.2 K and 0 T. This Jc value was about three times higher than that of the oxide bulk without Ag wire. The high alignment and dense structure of Bi-2223 phase was observed on the surface of Ag wires. It is mentioned that this structure brought about improvement of the Jc property. The mechanical property was estimated by a three point bending test. The bending stress was 60 MPa in Bi-2223 bulk without Ag wire, and 20 MPa in the composite with twenty-four Ag wires. The Bi-2223 bulk without Ag wire fractured separately after the maximum bending stress. It was noteworthy, however, that the composites did not fracture but only small cracks were induced after the maximum bending stress.