Development of Bi-2212 wires for practical applications using groove-rolling as an alternative process

  • Dipartimento di Fisica - Aula 603
  • Seminario

Relatori

Dr. Andrea Malagoli
CNR-SPIN

Dettagli

Round wires made of multifilamentary Bi2Sr2CaCu2Ox (Bi-2212) are an appealing alternative to Coated Conductors for high magnetic field applications (> 25 T) such as accelerator dipoles and NMR magnets. The main drawback in obtaining high critical currents densities (Jc) in long-length wires is the internal gas pressure generated during the heat treatment, which expands the wire diameter and dedensifies the superconducting filaments. Different routes have been proposed to increase the density of the Bi-2212 filaments and as a consequence increase Jc along the conductor by acting on the final as-drawn wire through cold isostatic pressure (CIPping) and swaging after drawing or through a very high (up to 100 bar) over pressure (OP) applied during heat treatment. 

At CNR-SPIN we tried to overcome this issue pursuing a different approach, i.e. changing the fabrication process in order to avoid as much as possible the porosity inside the as prepared wire. In particular, we applied the groove-rolling at different stages of the deformation process, obtained a larger powders compaction with respect to the drawing, and fabricated samples with round, square or rectangular shape depending on the application requirements.

Through a comparison between the Jc values measured in open- and closed-ends samples, we demonstrate the capability of this alternative deformation process of increasing the density in Bi-2212 wires.