Development of Superconducting Materials for Use in Magnet Applications: Nb3Sn Flux Pinning and Bi-2212 Magnetic Texturing
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The objective of this study was to develop techniques to be used in the manufacture of superconducting round wires for use in magnet applications. Nb3Sn and Bi-2212 are superconducting materials currently being developed for the next generation of magnet technology. Flux pinning in Nb3Sn has yet to be optimized, and the current carrying capacity of Bi-2212 is significantly lower than what is needed for practical use in high field magnets. Processes developed for the manufacture of Nb3Sn and Bi-2212 as round wires are presented and discussed. Processes were developed to increase flux pinning in Nb3Sn by utilizing powder metallurgy techniques to introduce a heterogeneously homogenous distribution of nanoscale inclusions of candidate materials in Nb rod. The Nb rod is to be used in the fabrication of high-performance Nb3Sn superconducting wire via a Powder-in-Tube method, in which the inclusions would act as artificial pinning centers. Consolidation of the powders via cold isostatic pressing proved problematic due to the high oxygen content of commercially available Nb powder. Severe plastic deformation of Nb was investigated as a method to produce low oxygen content Nb powder. The prospect of using an inductively coupled plasma torch to remove the oxygen from commercially available Nb powder is also discussed. An attempt was made to increase the current carrying capabilities of Bi-2212 by developing a procedure for magnetically texturing Bi-2212 powder with the goal of producing an Ag/Bi-2212 multifilamentary round wire with superior properties in high magnetic fields. In currently produced Bi-2212 wires, the conducting planes of each crystal are poorly aligned, and as a result, current transport is diminished. This project involves suspending Bi-2212 in a liquid solution on a substrate in the presence of a magnetic field in order to texture the deposited powder. This is possible because of the anisotropic magnetic susceptibility of Bi-2212. The solvent is then evaporated, leaving only the Bi-2212 powder on the substrate. The development of this process entailed optimizing the deposition method and observing the magnetic orientation of the powder.
Rahmani, David G. (2010). Development of Superconducting Materials for Use in Magnet Applications: Nb3Sn Flux Pinning and Bi-2212 Magnetic Texturing. Texas A&M University. Available electronically from