Drawing of Ag-clad superconductor wires

Abstract

The powder-in-tube process has been widely used to fabricate long lengths of Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212) superconducting wires and tapes. However, there is not a good understanding of the processing variables involved in the wire-drawing process. Recent studies indicated that powder characteristics, such as particle size distribution and morphology, had a significant effect on the consolidation behaviour of Bi-2212 green compacts. In this investigation, silver-clad Bi-2212 composite wires containing powders of two different particle sizes were fabricated. The effects of initial packing density and sheath thickness on the characteristics of the wires, including elongation, silver:core ratio and relative core density, were investigated. It is observed that coarse powders with a wide particle size distribution produce wires with higher core density and a moderate benefit is obtained from higher initial powder packing density.

On the strain inhomogeneity in drawn copper wires

“…Inhomogeneity in wire microstructure would affect some of the physical properties such as; electrical conductivity, magnetic moments and current density [7][8][9] as well as the formability and mechanical properties of the wire in next drawing passes [3,10]. The factors that affect strain distribution in wire cross-section are die-angle, friction, reduction of area, number of drawing passes and the wire metallurgical history.…”

Effect of starting precursor onIcanisotropy in powder-in-tube (Bi, Pb)2223/Ag tapes

“…It is commonly agreed that the precursor powder has strong influence on the final properties of a superconducting tape [1][2][3][4]. Many benefits are attributed to low partial oxygen calcination of the starting precursors [5][6][7].…”