Abstract: A method of preparing wires or tapes including Bi-2223 superconductor material by providing oxide and carbonate sources of Bi, Sr, Ca, Cu and Pb, milling the material for a time not to exceed about 30 minutes but preferably not greater than 20 minutes to produce a homogeneous mixture. Then heat treating by calcining the milled mixture at a temperature of at least about 830° C. for a time not less than about 12 hours, followed by at least one additional milling for a time not to exceed about 20 minutes and one additional heat treatment, to produce an oxide powder having an average diameter in the 4 to 5 micron range. Then a silver or silver alloy tube is filled with the oxide powder, and shape formed into a rectangular tape. Then alternately thermally treating and mechanically working the tube filled with oxide powder by heating the filled tube to an elevated temperature of about 835° C. to 840° C. and reducing the diameter of the tube, repeating the thermal and mechanical treatment.

Abstract: A method of producing a high temperature long length coil of superconductor wire or tape having improved critical current densities by utilizing an in-line pressing operation to heal the microcracks in the tape or wire which were introduced in rolling and coiling operations. The material can be Bismuth-2223, Bismuth 2212, Thallium-1234 or any other high temperature superconducting material. In the case of the Bismuth-2223, an improved "powder-in-tube" processing operation is provided to utilize excess bismuth, calcium, and copper in the initial composition material, and forming a partially developed Bi-2223 phase in the precursor powder introduced into the silver tubes. The final product has a 90-100% Bi-2223 phase with fine dispersions of secondary phases, to provide improved flux pinning thereby improving the critical current density of the material.

Abstract: A method of producing a high temperature long length coil of superconductor wire is disclosed. The method utilizes the "powder-in-tube" method or a similar method to form a wire. The wire is then shaped into rectangular form and wound around a mandrell. Rings, having a gap exposing the superconductor inside the silver or silver alloy tube are formed by cutting the wound wire and the rings are pressed to their final thickness. Each ring is then coated with an insulator and filed on both an outer side of one end of the gap and on an inner side of the other end of the gap. The rings are then positioned adjacent one another such that the gaps are staggered. They are placed in a manner in which the exposed superconductor on an outer side of one ring is in contact with the exposed superconductor on the inner side of an adjacent ring. The rings are then clamped together and heated to merge the superconducting material by diffusion. A long length coil is thus formed from the rings that are clamped.