Current transport and microstructural development in BSCCO tapes and joints fabricated by groove rolling

摘要

The powder-in-tube technique, which includes wiredrawing and rolling, has been widely used to fabricatesuperconducting tapes for possible electric power applications. Inthe present study the starting billet was reduced in size by grooverolling instead of by wire drawing. To optimize the deformationand thermomechanical treatment processes, BSCCO wires ofvarious dimensions were fabricated. The wires were flat rolled to afinal thickness of 250 #mu#m. Short-length tapes were subjectedto a series of thermal and deformation steps. Phase developmentand microstructural development during the process weremonitored by XRD, SEM and TEM. Current transport propertiesof the tapes were determined in the temperature range of 20-77 Kin self-field. Thermomechanical treatment resulted in tapes withaverage critical current densities of 18000 A cm~-2 at 77 K. High-resolution electron microscopy revealed better texturing and grainstructure at the superconductor-silver interface. Superconductinglap- and butt-joints have been formed by a chemical etchingtechnique. Detailed microstructural and current transportproperties of the joints have also been measured.