FABRICATION OF SUPERCONDUCTING CERAMIC FILMENTS BY A VISCOUS SUSPENSION SPINNING PROCESS

EARLY EXPERIMENTS SHOWED THAT HIGH CRITICAL TEMPERATURE (TC)SUPERCONDUCTING FILAMENT CAN BE PRODUCED IN A CONTINUOUS FASHION BY A VISCOUS SUSPENSION SPINNING PROCESS (VSSP). VSSP IS A MODIFIED CELLULOSE FIBER MANUFACTURING PROCESS BASED ON ESTABLISHED MANUFACTURING TECHNOLOGIES AND USING EXISTING INSTALLED PRODUCTION EQUIPMENT. IN THE ENVISIONED PROCESS, A SUITABLE Y-BA- CU-O OR OTHER HIGH TC SUPERCONDUCTING FINE POWDER IS INCORPORATED INTO A DESTRUCTIBLE, FIBER-FORMING CARRIER. CARRIER FIBERS FILLED WITH SUPERCONDUCTING MATERIALS ARE FORMED IN THE USUAL WAY BY EITHER WET- OR DRY- SPINNING. THE DESTRUCTIBLE CARRIER IS THEN REMOVED, AND THE REMAINING POWDER SINTERED AND HEAT-TREATED TO YIELD COHERENT FILAMENTS. PRELIMINARY TESTS HAVE SHOWN PROMISE, BUT MORE WORK IS NEEDED BEFORE THEPROCESS YIELDS A PRACTICAL, FLEXIBLE SUPERCONDUCTING MULTIFILAMENT CABLE OR WIRE. FUNDAMENTAL EXPERIMENTS IN PHASE I WILL EXAMINE SUCH KEY AREAS AS THE ATTAINMENT OF A HIGH SOLID FRACTION IN THE "GREEN" FILAMENT, CONTROL OF VSSPWITH VARIOUS PARTICLE LOADINGS, MECHANICAL AND CRYSTALLIZATION TECHNIQUES FOR ACHIEVING PREFERRED CRYSTAL ORIENTATION, CHEMICAL REACTIONS BETWEEN CARRIER AND HIGH TC CERAMIC POWDERS AND THEIR EFFECT, "GREEN" FILAMENT MECHANICAL STRENGTH, AND PROCESS ISSUES WITH HIGH TEMPERATURE DENSIFICATION OF FILAMENTS. THE WORK PLAN IS FOCUSED ON MAXIMIZING BOTH THE CRITICAL CURRENT (JC) AND MECHANICAL STRENGTH OF THE SUPERCONDUCTING FILAMENTS.