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

Super BSCCO Family 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

Super BSCCO Family 3 Background - Materials High Tc Superconduction originates from crystal structure Bi 2 Sr 2 Ca 2 Cu 3 O 8 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

Super BSCCO Family 4 BSCCO-2212 Crystal Structure Bi Sr Ca Cu O Background - Materials Double Rocksalt followed by Double Perovskite BSCCO-2223: Quadruple Rocksalt followed by Triple Perovskite

Super BSCCO Family 5 Background - Phenomenon Covalent Cu-O bonding and Cu 3+ valence states leads to partly filled energy bands  Oxidation to Cu 3+ 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

Super BSCCO Family 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)

Super BSCCO Family 7 Background - Technology HTS wire Ship Propulsion/Generation, Industrial Motors, Condensers

Super BSCCO Family 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

Super BSCCO Family 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)

Super BSCCO Family 10 Project Layout and Time Line Investigation of Thermomechanical Processes  Cold Deformation: rolling, suspend under tension  Heat Treatment: 150 – 800 o C  Uniaxial Hot Deformation  Hot Isotactic Pressing: ensure no phase transformation  Directional Graingrowth: temperature gradient

Super BSCCO Family 11 Project Layout and Time Line Improving Superconductivity  Defined Processing Sequence  Determined Process Variables: T, t, P  Goal: J c of 200kA/cm 2  Measure of Success: I c, SEM, x-ray

Project Layout and Time Line 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

Super BSCCO Family 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  I c : D. Bono Locate Resource Facilities  Vander Sande: manufacturing of BSCCO tape  Hiping: American Superconductor

Super BSCCO Family 14 Identification of Main Risks Time Critical Step  Defining Processing Sequence  Determining Process Variables Measurement Errors  I c : 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

Super BSCCO Family 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