Effect of various mechanical deformation techniques on critical current densities of Ag/Bi-2223 tapes

We have systematically studied the reduction rate dependence of critical cu rrent densities J(c) of Ag/Bi-2223 tapes using three methods, including nor mal rolling, pressing and "sandwich" rolling. Experimental results show tha t J(c) dependence on the reduction rate for the three processes follows the same law. When the reduction rate increases, J(c) initially increases, rea ches a maximum and then reduces. The core density-reduction rate follows a corresponding trend, However, the maximum J(c) of the Ad/Bi-2223 tapes made using "sandwich" rolling is 35% higher than for those made using normal ro lling even though the tapes in both cases have the same core density. This indicates that "sandwich" rolling reduces the cracks along the transverse d irection in the tape in comparison with normal rolling. (C) 2001 Elsevier S cience B.V. All rights reserved.