Large critical current density improvement in Bi-2212 wires through groove-rolling process

TL;DR

This study demonstrates that using groove-rolling instead of traditional drawing significantly enhances the critical current density in Bi-2212 superconducting wires by reducing porosity and improving microstructure, leading to better performance and manufacturing efficiency.

Contribution

The paper introduces a groove-rolling deformation process that substantially improves critical current density and microstructure in Bi-2212 wires compared to conventional drawing methods.

Findings

Groove-rolled wires show a JC increase by about 3 times.

Groove-rolling improves microstructure and reduces porosity.

The new process is faster and more cost-effective.

Abstract

Recently the interest about Bi-2212 round wire superconductor for high magnetic field use has been enhancing despite the fact that an increase of the critical current is still needed to boost its successful use in such applications. Recent studies have demonstrated that the main obstacle to current flow, especially in long wires, is the residual porosity inside these Powder-In-Tube processed conductors which develops in bubbles-agglomeration when the Bi-2212 melts. Through this work we tried to overcome this issue acting on the wire densification by changing the deformation process. Here we show the effects of groove-rolling versus drawing process on the critical current density JC and on the microstructure. In particular, groove-rolled multifilamentary wires show a JC increased by a factor of about 3 with respect to drawn wires prepared with the same Bi-2212 powder and architecture. We think that this approach in the deformation process is able to produce the required improvements both because the superconducting properties are enhanced and because it makes the fabrication process faster and cheaper.