Dynamic heat treatment of BSCCO-2212 tapes with homogeneous properties and high critical current density

摘要

Melt-processed Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+x//Ag tapes are now commercially available in long lengths. The melting step, which is mostly important for tape performance is difficult to control on the industrial scale. A dynamic approach is proposed. The melting step and subsequent annealing (2212-formation) step are separated. For the melting step, the reel-to-reel transfer system through a 140-cm long furnace was developed. The maximum processing temperature in the hot zone can be controlled to within 1/spl deg/C; heating rate from 3000/spl deg/C/h to 30000/spl deg/C/h and cooling rate between 60/spl deg/C/h to 30000/spl deg/C/h. The effect of heat treatment parameters characterizing the melting step on the transport critical current densities at 4.2 K was studied and correlated to microstructure characterized by SEM/EDS and X-ray diffraction analyzes.