Manufacture of long lengths of HTSC wires by extrusion

Powders of YBa{sub 2}Cu{sub 3}O{sub 7} were prepared by co-precipitation using aqueous solution of nitrates and oxalic acid. Precipitated powders were then filtered and dried. The dried powders were calcined at 500C or 800C and mixed with 2wt% of hydroxypropylmethylcellulose and small amounts of water. Long lengths of superconducting YBa{sub 2}Cu{sub 3}O{sub 7} wires were fabricated by means of extrusion followed by sintering. The maximum critical current density, J{sub c}, 1,100 A/cm{sup 2} (in transport) was obtained for samples prepared from 500C calcined powder and sintered at 920C. To improve J{sub c}, Y211 phase was also introduced to the calcined powder mix and extruded with binder. The maximum J{sub c} obtained by these techniques was 200 A/cm{sup 2}. A long length of wire was also extruded from the mixture of calcined Y123 powder, HPMC and a small amount of water. J{sub c} measurements show sintered density and absence of macro-pores are critical to maintain J{sub c} values. In long lengths of wire for which this condition holds the reduction of J{sub c} value with wire distance is minimal.