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

Melt-processed Bi2Sr2Ca1Cu2O8+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 1degreesC; heating rate from 3000degreesC/h to 30000degreesC/h and cooling rate between 60degreesC/h to 30000degreesC/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.