USA As Represented by Secretary of the Navy

Barry A Bender

Louis E Toth

Darla Schrodt

Jay S Wallace

Roy J Rayne

Robert J Soulen, Jr

Steven H Lawrence

L David Jones

A process for producing the 2223 phase of (Pb,Bi)SrCaCuO that is much faster than existing processes has the steps of: calcining a precursor powder mixture while maintaining intimate mixing of this precursor mixture by intermediate grindings during calcination; compressing the calcination product into a consolidated body; and heating the calcination product while maintaining intimate mixing of the calcination product, to form essentially phase pure 2223 (Pb,Bi)SrCaCu). A fast process for making a (Pb,Bi)SrCaCuO part with a high J.sub.c has the steps of: pressing calcined and reacted (Pb,Bi)SrCaCuO powder into a green body having the shaped of the part; and sintering the green body for a selected time, most preferably between 6 and 8 hours, that is long enough to establish superconducting electrical contact between grains of (Pb,Bi)SrCaCuO but short enough to prevent void formation or part shape distortion. The part made by this process has a high density, at least about 4 or 5 g/cm.sup.3.

Process for making superconducting PBSCCO and PBSCCO parts

Silicon carbide fibers which are derived from oligomeric and/or polymeric ecursors are modified and strengthened by annealing the silicon carbide fiber at temperatures in excess of 800.degree. C. under a nitrogen atmosphere in the presence of carbon particles. The modified fibers can be used to make ceramic, metal, and plastic composites.

Method of thermochemically treating silicon carbide fibers derived from

A machinable high Tc ceramic superconductor is formed by weighing and mixing appropriate stoichiometric amounts of Bi.sub.2 O.sub.3, SrCO.sub.3, CaCO.sub.3, and CuO (BSCCO), removing carbonates from the mixture, melting the mixture, casting the melted mixture into a mold, and inducing superconductivity and growth of randomly oriented platelets in the cast.

Machinable oxide ceramic

Silicon carbide fibers which are derived from oligomeric and/or polymeric precursors are modified and strengthened in annealing the silicon carbide fiber at temperatures in excess of 800.degree. C. under a nitrogen atmosphere in the presence of carbon particles. The modified fibers can be used to make ceramic, metal, and plastsic composites.

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Alexandria, VA, United States of America

Barry A Bender