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Thermomechanical Processing of High T c Superconducting Wire

Thermomechanical Processing of High T c Superconducting Wire. Super BSCCO Family Y. King S. Maltas B. Cooper C. Bjelkengren. Project Goal. Improve critical current through BSCCO-2223 ceramic encased in a silver tape. Strategy → Improve texture. Texture Analysis.

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Thermomechanical Processing of High T c Superconducting Wire

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  1. Thermomechanical Processing of High Tc Superconducting Wire Super BSCCO Family Y. King S. Maltas B. Cooper C. Bjelkengren

  2. Project Goal • Improve critical current through BSCCO-2223 ceramic encased in a silver tape. • Strategy → Improve texture Super BSCCO Family 2

  3. Texture Analysis • Why is texture important? Super BSCCO Family 3

  4. Texture Analysis • Why is texture important? Current flows along Cu-O planes Super BSCCO Family 4

  5. Texture Analysis • Why is texture important? Bad Good Worst Super BSCCO Family 5

  6. Project Goal Strategy • Choose most effective thermomechanical processing • How? – Evaluate • Ic • 150 A • Texture • Squeeze out the voids – area fraction from SEM • Lotgering factor – F-factor from XRD Super BSCCO Family 6

  7. Gantt Chart Super BSCCO Family 7

  8. 2223-BSCCO Properties Volume % ~ 60 % BSCCO A cross section ~ 0.9 mm2 4.14 mm Tc: 110 K Bc: 10-2 T Ic: 110 A 0.22 mm ST Super BSCCO Family 8

  9. Critical Current Measurement Super BSCCO Family 9

  10. Critical Current Measurement Super BSCCO Family 10

  11. Critical Current Measurement IC = 110 A Atotal = 4.14 x 0.22 mm2 ABSCCO = 60 % Atotal JE (engineering current density) = IC / Atotal = 121 A/mm2 JC (critical current density) = IC / ABSCCO = 200 A/mm2 Super BSCCO Family 11

  12. Texture Analysis • How do we measure texture? Qualitative: SEM examination of physical grain alignment, and size and concentration of voids. Answers the question: Do visual changes correlate to actual improvements in Ic ? Super BSCCO Family 12

  13. Texture Analysis - SEM Courtesy: Justin Schwartz (FAMU-FSU) Super BSCCO Family 13

  14. Texture Analysis • How do we measure texture? Quantitative: X-Ray Diffraction Lotgering Factor, F, which can be calculated: F = (P – Po) / (1-Po) Super BSCCO Family 14

  15. Texture Analysis - XRD Courtesy: Justin Schwartz (FAMU-FSU) Super BSCCO Family 15

  16. Project Goal Strategy • Methods for improving texture: • Rolling (hot or cold) Super BSCCO Family 16

  17. Rolling (hot and cold) • l1 = 2.02 x l0 • w1 = 1.05 x l0 • t1 = 0.47 x t0 Super BSCCO Family 17

  18. Project Goal Strategy • Methods for improving texture: • Uniaxial deformation (hot or cold) Super BSCCO Family 18

  19. Uniaxial Tensile Test (hot and cold) • YS of Ag: 1.4 x 108 Pa • x-section: 9.1 x 10-7 m2 • F applied: 127.5 N Super BSCCO Family 19

  20. Project Goal Strategy • Methods for improving texture: • Hot isostatic pressing Super BSCCO Family 20

  21. Hot Isostatic Pressing • t ~ 40 hours • T ~ 400/500 oC • P ~ 70 MPa • Ag-based solder • Annealing to reestablish Ox Super BSCCO Family 21

  22. Hot Isostatic Pressing T • Pressure, Temperature, time • Thermal diffusivity of oxygen across Ag • Annealing 70 MPa 500 oC t 40 h Super BSCCO Family 22

  23. Project Goal Strategy • Methods for improving texture: • Directional grain growth Super BSCCO Family 23

  24. Directional Grain growth T = 860 oC v = ? T = 760 oC Super BSCCO Family 24

  25. Option: Bonus Prototype Super BSCCO Family 25

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