High pressure oxidation of precursor alloys
AssigneeAmerican Superconductor Corporation
InventorsAlexander Otto, Lawrence J. Masur, Eric R. Podtburg, Kenneth H. Sandhage
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Abstract
A method for forming unsegregated metal oxide-silver composites includes preparing a precursor alloy comprising silver and precursor elements of a desired metal oxide and oxidizing the alloy under conditions of high oxygen activity selected to permit diffusion of oxygen into silver while significantly restricting the diffusion of the precursor elements into silver, such that oxidation of the precursor elements to the metal oxide occurs before diffusion of the metallic elements into silver. Further processing of the metal oxide composite affords an oxide superconducting composite with a highly unsegregated microstructure.
Claims33
A method for preparing an unsegregated metal oxide/silver composite, comprising the steps of:
- preparing a precursor alloy comprising precursor elements in a stoichiometry sufficient to provide a complex metal oxide, the precursor alloy disposed within a silver matrix;
- and
- oxidizing the precursor alloy under a condition wherein oxygen activity is equivalent to the activity of pure oxygen in its gaseous form (O.sub.2) at a temperature greater than 200.degree. C. and at a pressure greater than ambient selected to permit diffusion of oxygen through the silver matrix and at a temperature sufficiently low to significantly restrict the diffusion of the precursor elements away from the precursor alloy phase and into the silver matrix, such that the stoichiometry of the precursor elements throughout the precursor alloy phase is substantially preserved during the oxidation, whereby a complex metal oxide is obtained.
A method for preparing an unsegregated oxide superconductor/silver composite, comprising the steps of:
- preparing a precursor alloy, the precursor alloy comprising precursor elements in a stoichiometry sufficient to provide an oxide superconductor, the precursor alloy disposed within a silver matrix;
- oxidizing the precursor alloy under a condition wherein oxygen activity is equivalent to the activity of pure oxygen in its gaseous form (O.sub.2) at a temperature greater than 200.degree. C. and at a pressure greater than ambient selected to permit diffusion of oxygen through the silver matrix and at a temperature sufficiently low to significantly restrict the diffusion of the precursor elements away from the precursor alloy phase and into the silver matrix, such that the stoichiometry of the precursor elements throughout the precursor alloy is substantially preserved during the oxidation, whereby a corresponding metal oxide is obtained;
- and
- heating the corresponding metal oxide at a temperature and pressure selected to convert the metal oxide into the oxide superconductor.
Dependencies are inferred from the claim text.