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Thermomechanical Processing of High T c Superconducting Wire

Explore strategies to improve critical current by enhancing texture analysis in BSCCO superconducting wire, incorporating rolling, uniaxial deformation, and hot isostatic pressing methods. Evaluate Lotgering factor and grain alignment using SEM and XRD techniques.

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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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