The influence of heating temperature on the superconductingproperties of silver-gold sheathed Bi-2223 tapes destined for powerapplications

摘要

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 Jc up to 20 000 A cm-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°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 (Ic 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