Processing and fabrication of YBa sub 2 Cu sub 3 O sub x /Ag composite wires and coils

Silver was added to YBa{sub 2}Cu{sub 3}O{sub x} (123) powder by a melt technique using AgNO{sub 3} and heated to {approximately}600{degree}C to decompose the nitrate. This process yields 123 powder that is uniformly coated with Ag, as indicated by optical and scanning electron microscopy (SEM). The composite power is formed into rods ({approximately}4 mm diameter) via drawing and swaging through conical converging dies. Wires of finer diameter ({approximately}1 mm) and substantially greater linear uniformity have been produced by slurry extrusion of the composite powder in a polymeric vehicle. Transport critical current density, J{sub c}, of these wires at present is about 750 A/cm{sup 2}. This value may be expected to rise due to further reduction of second phase impurities localized at grain boundaries and better understanding of the Ag/superconductor interface. This paper describes the wire fabrication in some detail and discusses the results of microscopic analyses by scanning electron microscopy (SEM), x-ray photoemission spectroscopy (XPS), and x-ray diffraction (XRD). 11 refs., 4 figs., 1 tab.