The influence of heating temperature on the superconducting properties of silver-gold sheathed Bi-2223 tapes destined for power applications

For power engineering applications using HTS conductors, long-length Ag-Au sheathed Bi-2223 tapes are being developed. By a continuous fabrication process (rolling), tapes with J/sub c/ up to 20 000 A cm/sup -2/ (77 K, 0 T) have fabricated using the powder in tube method. The tapes were heat treated in the temperature range of 805-835/spl deg/C in an atmosphere of 8% oxygen in nitrogen. The influence of temperature and time on the evolution of the superconducting properties is investigated by means of electric transport current measurements (I/sub c/ and its distribution). Phase development at different processing stages is examined by XRD. The microstructure and phase assemblage at different heating temperatures are characterized with SEM/EDX. The critical current distribution in the tapes is studied by analyzing the second differential of the V-I curves and the effects of cracks and secondary phases are discussed.