Influence of partial oxygen pressure on the processing of Ag-sheathed BSCCO-2223 tapes

The effect of sintering in various oxygen atmospheres on transport J(c) has been investigated. The results of the peak J(c) with total sintering time are presented for each partial oxygen pressure (P-O2 = 0.04, 0.075, 0.21). Two important processing parameters of tapes were adjusted to ensure a fair comparison of each P-O2. Firstly, as the melting temperature of BSCCO decreases with decreasing P-O2, it was necessary to alter the sintering temperatures to maintain the same subcooling for each P-O2. Secondly, the first and second intermediate rollings of the tapes were performed when there were equal amounts of 2223 phase. The peaks in J(c) against total sintering time occurred at 200 h for P-O2 = 0.21, 45 h for P-O2 = 0.075, and 90 h for P-O2 = 0.04. This relates to the stability range and the incubation time of BSCCO-2223 in P-O2 and could be an important tool to reduce the long processing time of optimized tapes. (C) 1997 Published by Elsevier Science Ltd.