Fabrication and characterization of green-state Bi-2212 ribbons

Abstract

The authors report on the development of a mechanically textured, low porosity Bi-2212 ribbon. The ribbons are fabricated by compacting fine-powder Bi-2212 in a counterrotating roll set. Microstructure and texture of the as rolled ribbons are reported and compared to green-state cores from multifilament wires processed using the oxide-powder in-tube process.

Studies of porosity, connectivity, and parasitic phases in textured Bi-2212/Ag after non-melt heat treatments

“…The density of the pellet likewise increases, even though no compression is applied during or after sintering. The density after sintering at 875 °C for 24 hours is very nearly full solid density (6.6 g/cm 3 ). The texture parameter increases significantly.…”

“…These results are very encouraging. If we can fabricate the continuous ribbons of textured Bi-2212 reported in a companion paper [3] into 'jelly-roll' billets and then extrude and draw them into wire, the sintering process evaluated here should provide a basis to develop connectivity without the necessity of melting the Bi-2212 phase.…”

“…The method begins with a procedure by which a continuous ribbon of highly textured Bi-2212 fine powder on a silver foil substrate was formed. This procedure has been discussed in a previous paper [2] and has now been successfully implemented as reported in another paper at this conference [3]. It continues with a procedure by which the textured layer was formed into a 'jelly-roll' round billet which will be extruded and drawn to fine-wire dimensions.…”