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EF 152 Materials Recitation February 3, 2009

EF 152 Materials Recitation February 3, 2009. Materials Science and Engineering Department. Materials Recitation. Space Elevator Material Requirements Affect of Heat Treatment Demo Material Applications Heat Sink Biomimetic Lens SpaceShipOne Hot Wire & Shape Memory Demo

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EF 152 Materials Recitation February 3, 2009

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  1. EF 152Materials RecitationFebruary 3, 2009 Materials Science and Engineering Department

  2. Materials Recitation • Space Elevator Material Requirements • Affect of Heat Treatment Demo • Material Applications • Heat Sink • Biomimetic Lens • SpaceShipOne • Hot Wire & Shape Memory Demo • MSE Dept. Information

  3. Space Elevator

  4. Lifter

  5. Space Elevator • rocket: $20,000/kg to orbit • elevator: $200/kg to orbit • elevator much safer • no rockets • no re-entry heat • ~$10 billion to build elevator • NASA budget = $15 billion/yr • $0.5 billion per shuttle launch • 8 days one way • material for cable?

  6. Material requirements for cable? strength density

  7. Geostationary Orbit Geostationary: satellite stays above same point on earth’s surface (geosynchronous) v Fg R

  8. Force on Cable • Cable must support weight of cable beneath it

  9. Material Requirement for Cable “Specific Strength”

  10. Strength

  11. Density

  12. Specific Strength

  13. σUTS/ρ = 5.3E7 m2/s2 Specific Strength

  14. Carbon Nanotubes • 1st produced in 1991 • C=C double bonds  stronger than diamond • ~ 1 nm in diameter

  15. Carbon Nanotubes • 100 X stronger than diamond • 1/6 density of steel • up to 500 X specific strength of steel • ρ = 1,300 kg/m3 • highest measured strength = 63 GPa •  4.8E7 m2/s2  90% of target • theoretical strength = 150 GPa •  11.4E7 m2/s2 •  suitable for space elevator cable

  16. Carbon Nanotubes Challenges • CNTs are 4 cm long, 1 nm diameter • need 36,000 km long, 0.5 mm diameter cable • composites containing 50% CNTs •  binding between CNTs and matrix • km long composite fibers (3% CNT) have been produced with 2 GPa strength • twisted CNT yarn • Cost, ~ $25,000 per kg

  17. Affect of Heat Treatment Brass Tool Steel

  18. Processing Properties MATERIALS DEVELOPMENT Materials Science & Engineering Engineering Science Science Structure

  19. Thermal Management Heat generated by electronic devices must be dissipated to improve reliability and prevent failure.

  20. Thermal Management Heat Sink Design

  21. Thermal Management Which has highest thermal conductivity? • Aluminum • Diamond • Gold • Silver

  22. Thermal Management

  23. Synthetic Diamond • Chemical Vapor Deposition (CVD) • methane (CH4) is heated: CH4 C + 4H • gaseous C can deposit on substrate as diamond

  24. Synthetic Diamond Problems • Difficult to produce large areas (cm2) • Slow growth rates • Cost

  25. Lenses in Nature • Hierarchical layered protein structures • Refractive index gradients • Enhance focusing power • Correct aberrations • Reduce number of components needed for optical system

  26. Traditional Lens • Focus is a result of geometry and refraction • Refractive index does not vary within lens

  27. Focusing by an index gradient alone

  28. Multilayer Polymer Gradient Index (GRIN) Lens(Case Western Reserve University*) * funded by DARPA

  29. Multilayer Films • 10 splittings  2048 layers • 50 μm film  24 nm layers (must be < 50 nm for transmission) • Polycarbonate (PC), n = 1.58 • CD, DVD substrates, eyeglasses, water bottles • Poly(methyl methacrylate) (PMMA), n = 1.49 • Plexiglass, latex paint, countertops, lenses, aircraft cockpits

  30. Multilayer Films Refractive index of film corresponds to a thickness-weighted average of the indices of the component polymers

  31. 100/0 PMMA/PC, n = 1.490 99/1 PMMA/PC, n = 1.491 98/2 PMMA/PC, n = 1.492 . . . 50/50 PMMA/PC, n = 1.535 . . . 2/98 PMMA/PC, n = 1.578 1/99 PMMA/PC, n = 1.579 0/100 PMMA/PC, n = 1.580 GRIN Film

  32. GRIN Lens Fabrication

  33. X-Prize • US $10M prize for the first non-government organization to launch a reusable manned spacecraft into space twice within two weeks • SpaceShipOne, October 2004

  34. X-Prize

  35. SpaceShipOne • produced by Scaled Composites, LLC. • designed by Burt Rutan • project funded at $20M by Paul Allen (Microsoft) • carried to 14 km by White Knight aircraft (afterburning twin turbojets) • hybrid rocket motor generates 88 kN thrust for 87 sec. • reached altitude of112 km • now on display at National Air and Space Museum

  36. WhiteKnightOne and SpaceShipOne

  37. SpaceShipTwo • produced by Scaled Composites & Virgin (Richard Branson) • 2X size of SpaceShipOne • private spaceflight service starting 2009 or 2010 • two pilots and six passengers • 110 km target altitude • carried to 15 km by White Knight Two • $200,000 per flight • 200 customers have pre-paid • passengers must pass 6-8 g centifruge test

  38. Materials • Carbon fiber composites have excellent strength to weight ratio (specific strength) • Glass and Kevlar fibers also used • High performance, toughened epoxy matrix • Carbon fiber panels sandwiched around honeycomb core • White Knight Two • largest all-carbon-fiber aircraft ever built • 140 ft wing spar is the longest single carbon composite aviation component ever manufactured • most fuel efficient airplane ever created

  39. Hot Wire & Shape Memory Demonstrations

  40. MSE at UT • Class Size ~ 10-15 per year • Scholarships, ~ 75% receiving scholarships from dept: $800 - $2600 per year • 28 Faculty • ~ $5 M in annual research funding • UG research, thesis or paid

  41. MSE Scholarships

  42. MSE CurriculumFundamentals • Thermodynamics • Kinetics & Transport Phenomena • Processing • Mechanical Behavior • Diffusion & Phase Transformations • Structural Characterization • Materials Lab (2 semesters)

  43. MSE CurriculumMaterial Classes • Polymers • Ceramics • Metal Alloys • Electrical & Optical Materials

  44. MSE CurriculumDesign • Materials Selection • Materials Design Electives • Cell & Tissue- Biomaterials Interaction • Intermetallics & Composites • Advanced Biomaterials • Electronic Devices • Polymer Processing • Biomaterials • Polymer Engineering

  45. Biomaterials Concentration • 4 required courses • 2 MSE 4XX Electives • 2 Technical Electives • Nanomaterials Concentration planned for 2010-2011 Catalog

  46. Research Opportunities • ~ $5 M in annual research funding • Subsidized research opportunities for freshmen & sophomores • Several research opportunities at ORNL • Recent undergraduate research topics include • Piezoelectric Polymer Fibers • Computer Modeling of Micro-Scale Grains • Infrared Dichroism of Nonwoven Polymer Fibers • Nanocrystalline Biosynthesized Magnetite • Retained Austenite in Magnetically Processed Steel • Processing of Graphite Carbon Foams

  47. For more information, contact: Dr. Kevin Kit kkit@utk.edu 510 Dougherty 974-7055

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