EFFECT OF ROLLING REDUCTION ON THE TRANSPORT PROPERTY, MICROSTRUCTURE, PHASE-FORMATION AND FILL FACTOR OF HIGH-T-C SUPERCONDUCTING BI-(PB)-SR-CA-CU-O TAPES

Well-controlled intermediate deformation between sintering stages of ( Bi,Pb)(2)Sr2Ca2Cu3Ox tapes is crucial in achieving high critical curre nt density. This deformation, whether by rolling or pressing, depends on factors such as the compositional phase, the degree of microcracks, sintering periods or duration and sintering temperature. For rolling, additional factors such as roller size and rolling speed might also n eed to be taken into consideration. These factors together might then give an indication as to how much reduction is best between sintering stages. Here, it is shown that there is indeed an optimal 'window' of reduction for intermediate rolling (at room temperature) between sinte ring stages. For a particular temperature of sintering, this window va ries depending on the time of sintering and phase composition after a certain sintering period. It is found that the degree of intermediate deformation does certainly dictate the transformation rate of the high -T-c phase as well as determine the tape's final microstructure and fi ll factor. (C) 1996 Published by Elsevier Science Limited