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Thermomechanical Processing of High T c Superconducting Wire. Super BSCCO Family C. Bjelkengren B. Cooper Y. King S. Maltas. Superconductivity Review. High Tc Superconduction originates from crystal structure Highly anisotropic (superconduction along Cu-O planes) - PowerPoint PPT Presentation
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Thermomechanical Processing of High Tc Superconducting Wire
Super BSCCO Family
C. BjelkengrenB. CooperY. KingS. Maltas
Super BSCCO Family2
Superconductivity Review High Tc Superconduction originates from crystal structure
Highly anisotropic (superconduction along Cu-O planes) Maintain grain/Cu-O plane alignment to maximize
superconduction
Cu3+ valence states lead to partly filled energy bands Oxidation to Cu3+ leads to p-type conductivity Weak localization of valence electrons (low ionic
character) Alkaline and rare earth metals act as charge reservoirs
Super BSCCO Family3
Basic Plan and Time Line Improve the superconductivity through various
thermomechanical processes to align grains and Cu-O planes
Week 1-3: Characterization of BSCCO Tape
Week 4-8: Investigation of Thermomechanical Processes
Week 9-14: Improving Superconductivity/Working on Prototype
Super BSCCO Family4
Weeks 1-3 Characterization of BSCCO Tape
Preparation of Samples: long/short transverse, filet
Light Microscopy: structural observations
Scanning Electron Microscopy: qualitative microstructural
observations
Differential Scanning Calorimetery: phase transition identification
Critical Current Measurement: initial property characterization
X-ray Analysis: Lotgering factor - quantitatively measures texture
by the intensity of the 2 peaks where 0=completely random and
1=completely textured
Super BSCCO Family5
Sample Preparation Characterization of BSCCO Tape
Preparation of Samples in Epoxy: Short transverse ||||||
Long transverse ||||||
Filet ||||||
Polished to expose BSSCO
.
Super BSCCO Family6
Samples:Short Transverse Cut Sample in Epoxy and Coated in Gold (for SEM)
Long Transverse Cut Sample in Epoxy and Coated in Gold (for SEM)
Filet Cut Sample in Epoxy
Super BSCCO Family7
Light Microscopy: Structural observations
ST 165x ST 330x
Super BSCCO Family8
Light Microscopy: Structural observations
LT 660x Fillet 165x
Super BSCCO Family9
Scanning Electron Microscopy Qualitative Microstructural Observations
ST 420x LT 420x
Super BSCCO Family10
Differential Scanning Calorimetery Phase Transition Identification
-170 deg C to 300 deg C @ 20 C/min 200 deg C to 600 deg C @ 20 C/min
Super BSCCO Family11
Work Today Critical Current Measurement: initial property characterization
Setup Built and Ready for Testing
X-ray Analysis: Lotgering factor - quantitatively measures texture
by the intensity of the 2 peaks where 0=completely random and
1=completely textured Samples Polished and Ready for Testing
Super BSCCO Family12
In the Next Few Weeks… Investigation effects of thermomechanical processes on
superconductivity
Cold Deformation: rolling, suspend under tension
Heat Treatment: 150 – 800 oC
Uniaxial Hot Deformation
Hot Isotactic Pressing
Directional Graingrowth: temperature gradient
Super BSCCO Family13
Improving Superconductivity Improving Superconductivity
Defined Processing Sequence
Determine Optimal Processing Variables: T, t, P
Measure of Success Ic, x-ray, SEM
Quantitative: Ic = 150 kA, Improve Lotgering Factor
Qualitative: SEM
Super BSCCO Family14
Areas of Further Research Research Thermomechanical Processes
Research Prototype Ideas
Locate Resource Facilities Cold Deformation
Heat Treatment
Uniaxial Hot Deformation
Hot Isotactic Pressing
Directional Graingrowth