OXIDE DISPERSION STRENGTHENED SILVER FOR USE IN HIGH-TEMPERATURE SUPERCONDUCTOR COMPOSITE WIRES

THE STRENGTHENING OF HIGH-TEMPERATURE SUPERCONDUCTING (HTS)COMPOSITE WIRES WITH OXIDE DISPERSION STRENGTHENED (ODS) SILVER IS THE SUBJECT OF THIS PROJECT. STATE-OF-THE-ART HTS COMPOSITE WIRES CONSIST OF CERAMIC SUPERCONDUCTOR FILAMENTS ENCASED IN A SILVER (AG) SHEATH. FOR REASONS OF CHEMICAL COMPATIBILITY AND OXYGEN PERMEABILITY, SILVER IS THE ONLY MATERIAL THAT CAN BE USED TO SHEATH THE HTS. HOWEVER, THE CURRENT METHOD OF MANUFACTURE WEAKENS THE AG SHEATH, RESULTING IN REDUCED HTS COMPOSITE STRENGTHS. THE LOW STRENGTHS ARE A MAJOR OBSTACLE IN THE DEVELOPMENT OF HTS WIRES FOR APPLICATIONS REQUIRING HIGH STRENGTH SUCH AS POWER TRANSMISSION CABLES, SUPERCONDUCTING MAGNETIC ENERGY STORAGE (SMES), CURRENT LIMITERS, AND MOTORS. THE ONLY KNOWN METHOD OF INCREASING THE STRENGTH OF SHEATH, WHILE MAINTAINING THE CHEMICAL COMPATIBILITY AND OXYGEN PERMEABILITY OF AG IS ODS. ODS IS CURRENTLY USED TO STRENGTHEN AG FOR RELATIVELY LOW-TEMPERATURE APPLICAATIONS. HOWEVER, HIGH TEMPERATURES ARE USED IN THE MANUFACTURE OF HTS COMPOSITE WIRES, AND LITTLE IS KNOWN ABOUT THE HIGH TEMPERATURE CHARACTERISTICS OF ODS-AG MATERIALS. PHASE I WILL EVALUATE NOVEL ODS-AG MATERIALS, IN THE CONTEXT OF HTS COMPOSITES PROCESSING. TWO SYNTHESIS ROUTES TO FORM ODS-AG WILL BE EVALUATED IN PHASE I: INTERNAL OXIDATION OF A METALLIC ALLOY PRECURSOR AND POWER METALLURGY. AN ASSESSMENT OF THE FORMABILITY AND MECHANICAL PROPERTIES OF THE ODS-AG MATERIALS PRODUCED BY EACH ROUTE WILL BE MADE. MATERIALS PRODUCED USING THE TWO SYNTHESIS ROUTES WILL BE USED IN STATISTICALLY DESIGNED EXPERIMENTS, BASED ON PROCESS CONDITIONS SIMILAR TO THOSE USED TO FABRICATE HTS COMPOSITES. A QUATITATIVE EXPRESSION OF THE MECHANICAL PROPERTIES OF THE NOVEL ODS-AG MATERIALS AS A FUNCTION OF THE PROCESS PARAMETERS (TEMPERATURE, OXYGEN ACTIVITY, TIME, AND STRAIN) WILL BE ACHIEVED. PHASE II WILL BE DIRECTED TO THE FABRICATION AND TESTING OF HTS COMPOSITES USING THE OPTIMUM SHEATHING MATERIALS.