Explosive consolidation of (Bi,Pb)-Sr-Ca-Cu-O superconductor powders during powder-in-tube processing

摘要

Superconducting (2212) Bi-Sr-Ca-Cu-O (BSCCO) and BSCCO-Ag composites were explosively consolidated in silver tubing and then drawn and rolled into tapes. The silver-sheathed tapes were then subjected to repeated cycles of pressing and heat treatment, which resulted in enhanced texturing and grain growth and a subsequent increase in critical current density (J(sub c)). The effect of silver flake additions to the superconducting powder further increased texturing and J(sub c), with optimal properties occurring in powders with 10 vol.% silver flake. Density measurements on the superconductor tapes showed that near-theoretical densities had been achieved at the end of the thermomechanical treatment (TMT). Scanning electron microscopy indicated that grain alignment increased after TMT, with an apparent reduction in grain size after the fourth treatment. X-ray diffraction studies showed that grain orientation and conversion of 2212 to Bi(sub 2)Sr(sub 2)Ca(sub 2)Cu(sub 3)O(sub 10(minus)x) are improved when explosive consolidation is introduced before the drawing step in the powder-in-tube process.