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

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

Super BSCCO Family 3 Texture Analysis Why is texture important?

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

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

Super BSCCO Family 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 7 Gantt Chart 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

Super BSCCO Family BSCCO Properties ST 0.22 mm 4.14 mm Volume % ~ 60 % BSCCO T c : 110 K B c : T I c : 110 A A cross section ~ 0.9 mm 2

Super BSCCO Family 9 Critical Current Measurement

Super BSCCO Family 10 Critical Current Measurement

Super BSCCO Family 11 Critical Current Measurement I C = 110 A A total = 4.14 x 0.22 mm 2 A BSCCO = 60 % A total J E (engineering current density) = I C / A total = 121 A/mm 2 J C (critical current density) = I C / A BSCCO = 200 A/mm 2

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

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

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

Super BSCCO Family 17 Rolling (hot and cold) l 1 = 2.02 x l 0 w 1 = 1.05 x l 0 t 1 = 0.47 x t 0

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

Super BSCCO Family 19 Uniaxial Tensile Test (hot and cold) Y S of Ag: 1.4 x 10 8 Pa x-section: 9.1 x m 2 F applied: N

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

Super BSCCO Family 21 Hot Isostatic Pressing t ~ 40 hours T ~ 400/500 o C P ~ 70 MPa Ag-based solder Annealing to reestablish O x

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

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

Super BSCCO Family 24 Directional Grain growth T = 860 o C T = 760 o C v = ?

Super BSCCO Family 25 Option: Bonus Prototype