Thermomechanical Processing of High Tc Superconducting Wire

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Thermomechanical Processing of High Tc
Superconducting Wire

• Super BSCCO Family
• Y. King
• S. Maltas
• B. Cooper
• C. Bjelkengren

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Project Goal

• Improve critical current through BSCCO-2223
  ceramic encased in a silver tape.
• Strategy ? Improve texture

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Texture Analysis

• Why is texture important?

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Texture Analysis

• Why is texture important?
• Current flows along
• Cu-O planes

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Texture Analysis

• Why is texture important?

Bad
Good
Worst
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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

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Gantt Chart
  1 2 3 4 5 6 7 8 9 10 11 12 13 14
Characterization                            
Cold Rolling                            
Uniaxial Cold Deformation                            
Heat Treatment                          
Hot Isostatic Pressing                            
Directional Grain growth                            
Ideas For Application/Prototype                            
Improve Superconductivity, Jc                            
Work On Final Product                            
Final Presentation/Poster                            
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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
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Critical Current Measurement

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Critical Current Measurement

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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

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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 ?

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Texture Analysis - SEM

• Courtesy Justin Schwartz (FAMU-FSU)

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Texture Analysis

• How do we measure texture?
• Quantitative
• X-Ray Diffraction Lotgering Factor, F, which can
  be calculated
• F (P Po) / (1-Po)

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Texture Analysis - XRD

• Courtesy Justin Schwartz (FAMU-FSU)

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Project Goal Strategy

• Methods for improving texture
• Rolling (hot or cold)

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Rolling (hot and cold)

• l1 2.02 x l0
• w1 1.05 x l0
• t1 0.47 x t0

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Project Goal Strategy

• Methods for improving texture
• Uniaxial deformation (hot or cold)

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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

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Project Goal Strategy

• Methods for improving texture
• Hot isostatic pressing

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Hot Isostatic Pressing

• t 40 hours
• T 400/500 oC
• P 70 MPa
• Ag-based solder
• Annealing to reestablish Ox

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Hot Isostatic Pressing
T

• Pressure, Temperature, time
• Thermal diffusivity of oxygen across Ag
• Annealing

70 MPa
500 oC
t
40 h
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Project Goal Strategy

• Methods for improving texture
• Directional grain growth

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Directional Grain growth
T 860 oC
v ?
T 760 oC
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Option Bonus Prototype