Thermomechanical Processing of High Tc Superconducting Wire

1
Thermomechanical Processing of High Tc
Superconducting Wire

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

2
Outline

• Background
• Materials
• Phenomenon
• Technology
• Project Layout and Time Line
• Characterization of BSCCO Tape
• Investigation of Thermomechanical Processes
• Improvement of Superconductivity
• Areas of Further Research
• Identification of Main Risks
• Prospects and Potential Prototypes

3
Background - Materials

• High Tc Superconduction originates from crystal
  structure
• Bi2Sr2Ca2Cu3O8 BSCCO-2223
• Perovskite/Rocksalt derivatives with alternating
  
• (0 0 n) planes
• Highly anisotropic (superconduction along Cu-O
  planes)
• High degree of texturing required to keep
  grains/Cu-O planes aligned

4
Background - Materials

• BSCCO-2212
• Crystal Structure
• Bi
• Sr
• Ca
• Cu
• O

BSCCO-2223 Quadruple Rocksalt followed by Triple
Perovskite
Double Rocksalt followed by Double Perovskite
5
Background - Phenomenon

• Covalent Cu-O bonding and Cu3 valence states
  leads to partly filled energy bands
• Oxidation to Cu3 leaves a hole in the
  conduction band for p-type conductivity
• Weak localization of valence electrons (low
  ionic character)
• Alkaline and rare earth metals act as charge
  reservoirs

6
Background - Phenomenon

• Cooper pairs at critical low T
• Under an electric potential, electrons are
  paired by the temporary polarization of a cation
  core
• Phonons couple, rather than scatter, electrons
• Zero resistance, perfect diamagnetism (Meissner
  effect)

7
Background - Technology
HTS wire
Ship Propulsion/Generation, Industrial Motors,
Condensers
http//www.amersuper.com/products
8
Project Layout and Time Line

• Improving the Superconductivity
• Eliminating Porosity and Cracking
• Week 1-3 Characterization of BSCCO Tape
• Week 4-8 Investigation of Thermomechanical
  Processes
• Week 9-14 Improving Superconductivity/Working on
  Prototype

9
Project Layout and Time Line

• Characterization of BSCCO Tape
• Preparation of Samples long/short transverse,
  filet
• Light Microscopy structural observations
• Differential Scanning Calorimetery
  phasetransistion identification
• Critical Current Measurement initial property
  characterization
• Scanning Electron Microscopy qualitative
  microstructural observations
• x-ray Analysis quantitative texture observations
  (0-1)

10
Project Layout and Time Line

• Investigation of Thermomechanical Processes
• Cold Deformation rolling, suspend under tension
• Heat Treatment 150 800 oC
• Uniaxial Hot Deformation
• Hot Isotactic Pressing ensure no phase
  transformation
• Directional Graingrowth temperature gradient

11
Project Layout and Time Line

• Improving Superconductivity
• Defined Processing Sequence
• Determined Process Variables T, t, P
• Goal Jc of 200kA/cm2
• Measure of Success Ic, SEM, x-ray

12
Project Layout and Time Line
  1 2 3 4 5 6 7 8 9 10 11 12 13 14
Literature Search Reading                            
Update Webpage                            
Update Notebook                            
Presentaitons                            
Budget Control                            
Meeting With Vander Sande                            
Obtain Materials                            
Document I basic background                            
Characterize Microstructure                            
Document II microstructure and phase                            
Cold Deformation                            
Heat Treatement                            
Uniaxial Hot Deformation                            
Hot Isotactic Pressing                            
Directional Graingrowth                            
Document III thermomechanical processing                            
Ideas For Application/Prototype                            
Improve Superconductivity, Jc                            
Outside Facilities                            
Work On Final Product                            
Final Presentation                            
Poster                            
13
Areas of Further Research

• Reading
• Journals
• Research Thermomechanical Processes
• Research Prototype Ideas
• Self-user training
• SEM D. Bono, J. Adario
• x-ray J. Adario
• Ic D. Bono
• Locate Resource Facilities
• Vander Sande manufacturing of BSCCO tape
• Hiping American Superconductor

14
Identification of Main Risks

• Time Critical Step
• Defining Processing Sequence
• Determining Process Variables
• Measurement Errors
• Ic maintain constant measuring conditions
• x-ray separate readings of texture from BSCCO
  and Ag
• Contamination the sample might contain sulfur
  resides from manufacturing
• Prototype Development
• Does Postprocessing Affect Superconductivity
  bending etc

15
Prospects and Potential Prototypes

• General Benefits
• More Current / Area
• Higher Efficiency
• Less Material
• Lower Mass
• Lower Production and Transportation Costs
• Specific Applications
• Electric Power Transmission Lines
• Transformers
• Electromagnets
• Motors
• Magnetic Levitation