Functionally gradient superconducting foils by plasma spraying

Functionally gradient composite foils of Y–Ba–Cu–O and silver with a layer thickness of around 100 μm and certain flexibility, were produced by air plasma spraying. The superconducting phase is formed in sprayed composite foils only after annealing in flowing oxygen above 900 °C but can be improved by annealing first in argon at 850 °C prior to the oxygen annealing. The effect of argon pre-treatment was found to increase the grain size of YBa2Cu3O7-δ. The behaviour of the graded silver layer in improving the ductility and in the process of recovery of superconductivity of the sprayed coating was investigated. © 1998 Kluwer Academic Publishers