Contents I. Introduction
Bi-2223 superconductor sintered bulks have been used as a current leads for a liquid He-free cryocooler-cooled magnet and a current limiter [1]. Bi-2223 bulk, however, has some problems that limit the application field. One of the typical problems is that the critical current density of the bulk materials is much smaller than that of the wire and tape materials. Another is that the sintered bulk is fragile because Bi-2223 bulk is a ceramic material. We expect that including metal silver (Ag) in Bi-2223 bulk, analogous to the tape and wire materials, would improve the Jc property and mechanical property. In previous papers, we reported that the Jc of Bi-2223 bulks was improved by adding Ag sheet and wires [2]– [6]. This is because highly -axis oriented and densely structured Bi-2223 plate-like grains could be formed along the Ag sheet and wire. We also reported that the mechanical properties were improved by addition of Ag wires from results with a three point bending test [5] [6] [7]. Optical photograph of cross-section of the Bi-2223/Ag wire composite bulk. 24 wires of 0.4 mm in diameter.
