Nb-Al TYPE SUPERCONDUCTING WIRE HAVING STABILIZING COPPER DEPOSIT TENACIOUSLY ADHERENT THERETO AND PROCESS FOR PRODUCING THE SAME

摘要

An Nb-Al type superconducting wire which is in a state before transformation to an Nb3Al compound. It comprises an Nb-Al type wire in the state of a supersaturated solid solution, a nickel coating film as an interlayer, and a copper coating film tenaciously formed as a stabilizing material on the peripheral surface of the wire through the interlayer. It can be produced from an Nb-Al type wire in the state of a supersaturated solid solution obtained through cooling in liquid gallium, via the following steps: (a) a step in which a gallium residue adherent to the surface of the Nb-Al type wire is removed; (b) a step in which the Nb-Al type wire from which the gallium residue on the surface has been removed in the step (a) is degreased under such conditions as not to passivate the Nb-Al type wire and is then pickled; (c) a step in which the surface of the Nb-Al type wire pickled in the step (b) is electroplated with nickel in a nickel strike bath; and (d) a step in which the surface of the Nb-Al type wire electroplated with nickel in the step (c) is electroplated with copper. From this Nb-Al type superconducting wire, an Nb3Al compound type superconducting wire can be industrially advantageously produced which is useful in a magnet for nuclear fusion reactors, magnet for accelerators, and magnet for nuclear magnetic resonance (NMR) apparatuses having high resolution.