Characterizing superconducting BSSCO tapes and bulk joints

For many potential applications, long lengths of superconducting tapes and bulk materials with high current capacities are needed. Producing long lengths of superconducting bulk and tapes by joining is considered a challenge. Superconducting monofilament Bi(2223) tapes were fabricated using the powder in tube method with groove and flat rolling. The tapes were rolled to a final thickness of 250 μm. The tapes and bulk materials were processed using a combination of pressing and sintering. The average critical currents for the tapes and bulk materials were 70 and 180 A at 77 K and self field respectively. Superconducting tapes and bulk specimens were joined using lap and butt configurations and thermomechanically processed to make superconducting joints. The maximum joint efficiencies for the lap and butt joints were in the range of 30% to 100%. The phase changes and microstructural development in the joint region were investigated using hardness measurements, XRD and SEM.