earticle

영어

Bi-2212 (Bi2Sr2CaCu2O8+x) high temperature superconducting (HTS) wires are attracting significant attention in high field magnet applications due to their high engineering critical current density (Je) and excellent performance in high magnetic fields. However, the Ag/AgMg alloy matrix used in Bi-2212 wires exhibits a low elastic modulus (E = 70 GPa) and yield strength (σy < 100 MPa) [1], making the wires prone to deformation even under small loads, which leads to performance degradation. These low electromechanical properties impose strain-induced limitations on the performance of high-field solenoid magnets rather than current-induced limitations. To address this issue, enhancing the mechanical strength of Bi-2212 wires is essential. In this study, we aimed to improve the mechanical strength of Bi-2212 wires using a strip lamination technique. The Bi-2212 round wire was processed into a tape form through a flat-rolling process, and Inconel X-750 strips were bonded to both sides of the Bi-2212 tape using a bonding process, resulting in the fabrication of a final Inconel X-750 laminated sample with a thickness of 0.84 mm and a width of 1.88 mm. Tensile tests at cryogenic temperatures (77 K) revealed that the Inconel X-750 laminated sample achieved a strength of 278 MPa at a strain of 0.4 %, representing a twofold improvement compared to the original round wire. Additional investigations included filament area uniformity and Je property changes during the flat-rolling process, as well as interfacial analysis between the Bi-2212 tape and the Inconel X-750 strip during the heat treatment process.