Superconducting tapes are widely used in application where large lengths of materials are required to meet the high-power performance and stringent weight and size requirements. Silver-clad tapes of BPSCCO-2223 material can be produced from polyphase powders, which reactively sinter in suit to form the BPSCCO-2223. Optimum annealing temperatures and unique thermomechanical methods are necessary to achieve the highest critical current density in the tapes. Reactive sintering of polyphase tapes is extremely sensitive to annealing temperature. There is a narrow range of annealing temperature, and the optimum annealing temperature must be used to allow maximum transformation without decomposition of the 2223 phase.

Continued intermittent processing after initial grain-growth annealing is necessary to advance the chemical reaction and to promote grain texturing. The highest current density has been seen in BPSCCO tapes made from polyphase powder annealed for 350 h at 845℃ with three intermittent pressing cycles. Continued thermomechanical processing leads to a remarkable increase in current density as a result of improved grain texturing. Completion of the annealing process between 830 and 853℃ indicates that maximum transformation of 2212 to 2223 due to endothermic reaction takes place over this narrow temperature range. A suitable number of thermomechanical cycles and intermediate annealing times with minimum deformation are essential to achieve high current density.