Ef 152 materials recitation february 3 2009
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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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EF 152Materials RecitationFebruary 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

  • MSE Dept. Information


Space Elevator


Lifter


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?


Material requirements for cable?

strength

density


Geostationary Orbit

Geostationary: satellite stays above same point on earth’s surface (geosynchronous)

v

Fg

R


Force on Cable

  • Cable must support weight of cable beneath it


Material Requirement for Cable

“Specific Strength”


Strength


Density


Specific Strength


σUTS/ρ = 5.3E7 m2/s2

Specific Strength


Carbon Nanotubes

  • 1st produced in 1991

  • C=C double bonds  stronger than diamond

  • ~ 1 nm in diameter


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


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


Affect of Heat Treatment

Brass

Tool Steel


Processing

Properties

MATERIALS DEVELOPMENT

Materials Science & Engineering

Engineering

Science

Science

Structure


Thermal Management

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


Thermal Management

Heat Sink Design


Thermal Management

Which has highest thermal conductivity?

  • Aluminum

  • Diamond

  • Gold

  • Silver


Thermal Management


Synthetic Diamond

  • Chemical Vapor Deposition (CVD)

  • methane (CH4) is heated: CH4 C + 4H

  • gaseous C can deposit on substrate as diamond


Synthetic Diamond

Problems

  • Difficult to produce large areas (cm2)

  • Slow growth rates

  • Cost


Lenses in Nature

  • Hierarchical layered protein structures

  • Refractive index gradients

    • Enhance focusing power

    • Correct aberrations

    • Reduce number of components needed for optical system


Traditional Lens

  • Focus is a result of geometry and refraction

  • Refractive index does not vary within lens


Focusing by an index gradient alone


Multilayer Polymer Gradient Index (GRIN) Lens(Case Western Reserve University*)

* funded by DARPA


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


Multilayer Films

Refractive index of film corresponds to a thickness-weighted average of the indices of the component polymers


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


GRIN Lens Fabrication


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


X-Prize


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


WhiteKnightOne and SpaceShipOne


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


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


Hot Wire & Shape Memory Demonstrations


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


MSE Scholarships


MSE CurriculumFundamentals

  • Thermodynamics

  • Kinetics & Transport Phenomena

  • Processing

  • Mechanical Behavior

  • Diffusion & Phase Transformations

  • Structural Characterization

  • Materials Lab (2 semesters)


MSE CurriculumMaterial Classes

  • Polymers

  • Ceramics

  • Metal Alloys

  • Electrical & Optical Materials


MSE CurriculumDesign

  • Materials Selection

  • Materials Design

Electives

  • Cell & Tissue-

    Biomaterials Interaction

  • Intermetallics & Composites

  • Advanced Biomaterials

  • Electronic Devices

  • Polymer Processing

  • Biomaterials

  • Polymer Engineering


Biomaterials Concentration

  • 4 required courses

    • 2 MSE 4XX Electives

    • 2 Technical Electives

  • Nanomaterials Concentration planned for 2010-2011 Catalog


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


For more information, contact:

Dr. Kevin Kit

kkit@utk.edu

510 Dougherty

974-7055


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