PROCESSING YTTRIUM BARIUM COPPER-OXIDE SUPERCONDUCTOR IN NEAR-ZERO GRAVITY

The effects of processing YBa2Cu3Ox (Y123) superconductor in the near- zero gravity (0 g) environment provided by the NASA KC-135 airplane fl ying on parabolic trajectories were studied. A new sheet float zone fu rnace, designed for this study, enabled fast temperature ramps. Up to an 18 g sample was processed with each parabola. Samples of Y123 were processed as bulk sheets and composites containing Ag and Pd. The 0 g processed samples were multi-phase yet retained a localized Y123 stoic hiometry where a single ground-based (1 g) oxygen anneal at temperatur es of 800-degrees-C recovered nearly 100 vol% superconducting Y123. Th e 1 g processed control samples remained multi-phase after the same gr ound-based anneal with less than 45 vol% as superconducting Y123. The superconducting transition temperature was 91 K for both 0 g and 1 g p rocessed samples. Melt texturing of bulk Y123 in 0 g produced aligned grains about a factor of three larger than in analogous 1 g samples. T ransport-critical current densities were at or below 18 A/CM2, due to the formation of cracks caused by the rapid heating rates required by the short time at 0 g.