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 pro cess (rolling), tapes with J(c) up to 20000 Acm(-2) (77K, 0T) have been fab ricated using the powder in tube method. The tapes were heat treated in the temperature range of 805-835 degrees C in an atmosphere of 8% oxygen in ni trogen. The influence of temperature and time on the evolution of the super conducting properties is investigated by means of-electric transport curren t measurements (I, and its distribution). Phase development at different pr ocessing stages is examined by XRD. The microstructure and phase assemblage at different heating temperatures are characterized with SEM/EDX. The crit ical current distribution in the tapes is studied by analyzing the second d ifferential of the V-I curves and the effects of cracks and secondary phase s are discussed.