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 mu m 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 degrees C but can be improved by annealing first in argon at 850 degrees C prior to the oxygen annealing. The effect of argon pre-treatment was found to increase the grain size of YBa2Cu3O7-delta. 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. (C) 1998 Kluwer Academic Publishers.