EF 152
Materials Recitation
February 3, 2009
Materials Science and Engineering
Department
1
Materials Recitation
Space Elevator Material Requirements
Hot Wire & Shape Memory Demo
Material Applications



Heat Sink
Biomimetic Lens
SpaceShipOne
Affect of Heat Treatment Demo
MSE Dept. Information
2
Space Elevator
3
Lifter
4
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?
5
Material requirements for
cable?
strength
density
6
Geostationary Orbit
Geostationary: satellite
stays above same point on
earth’s surface
(geosynchronous)
man  Fgravity
2 R

hr
24 day
 3,600 sec
hr
v
Fg
R
mv 2
mmE
G 2
R
R
4 m 2 R
mmE
G 2
2
R
24  3600
R  42.24x10 6 m
7
Force on Cable
Cable must support weight of cable beneath it
dFgcable    r 2
GM
dR
2
R
R
cable
g
F
1
( R)    r GM 
dR
2
R
6 .45 E 6
2

   r 2 (6.67 E  11 kgm s 2 )(6 E 24 kg ) (6.45 E 6 m) 1  R 1
3
at R  42.24E6 m,
Fgcable  5.3E7 ms 2   r 2
2

cable

Fgcable
r
2
 5.3E7
m2
s2

8

Material Requirement for Cable
σUTS
Pa
m2
 5.3E 7 s 2  5.3E 7 kg/m3
ρ
“Specific Strength”
9
Strength
10
Density
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Specific Strength
Material
7075 T6 Al
Ti-6Al-4V
440A Stainless steel
Nylon 6,6
Polyester
Kevlar 49
Spectra 2000
Silicon Carbide
Silicon Nitride
Diamond
C fiber
E-glass
ρ (kg/m3)
2,800
4,430
7,800
1,140
1,250
1,440
970
3,200
3,300
3,400
1,790
2,580
σUTS (MPa) σUTS/ρ (m2/s2)
505
1,172
1,790
90
85
4,100
3,340
825
1,000
1,400
6,350
3,450
1.8E+05
2.6E+05
2.3E+05
7.9E+04
6.8E+04
2.8E+06
3.4E+06
2.6E+05
3.0E+05
4.1E+05
3.5E+06
1.3E+06
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Specific Strength
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Carbon Nanotubes
1st produced in 1991
C=C double bonds  stronger than diamond
~ 1 nm in diameter
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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
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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
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Hot Wire & Shape Memory
Demonstrations
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Thermal Management
Heat generated by electronic devices must be
dissipated to improve reliability and prevent failure.
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Thermal Management
Heat Sink Design
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Thermal Management
Which has highest thermal conductivity?
A. Aluminum
B. Diamond
C. Gold
D. Silver
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Thermal Management
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Synthetic Diamond
Chemical Vapor Deposition (CVD)
methane (CH4) is heated: CH4  C + 4H
gaseous C can deposit on substrate as diamond
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Synthetic Diamond
Problems
Difficult to produce large areas (cm2)
Slow growth rates
Cost
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Lenses in Nature
Hierarchical layered protein structures
Refractive index gradients

Enhance focusing power

Correct aberrations

Reduce number of components needed
for optical system
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Traditional Lens
Focus is a result of geometry and refraction
Refractive index does not vary within lens
25
Focusing by an index gradient alone
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Multilayer Polymer Gradient Index (GRIN) Lens
(Case Western Reserve University*)
* funded by DARPA
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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
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Multilayer Films
Refractive index of film corresponds to a thickness-weighted
average of the indices of the component polymers
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GRIN Film
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
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GRIN Lens Fabrication
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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
32
X-Prize
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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
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WhiteKnightOne and SpaceShipOne
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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
36
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
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Affect of Heat
Treatment
Brass
Tool Steel
38
Materials Science & Engineering
Processing
Engineering
Properties
Structure
MATERIALS DEVELOPMENT
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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
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MSE Scholarships
Freshman
$800 - $1,200 per year
Sophomore
$1,200 - $1,600 per year
Junior
$1,600 - $2,100 per year
Senior
$2,100 - $2,600 per year
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MSE Curriculum
Fundamentals
Thermodynamics
Kinetics & Transport Phenomena
Processing
Mechanical Behavior
Diffusion & Phase Transformations
Structural Characterization
Materials Lab (2 semesters)
42
MSE Curriculum
Material Classes
Polymers
Ceramics
Metal Alloys
Electrical & Optical Materials
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MSE Curriculum
Design
Materials Selection
Materials Design
Electives
Electronic Devices
Polymer Processing
Biomaterials
Polymer Engineering
Cell & TissueBiomaterials Interaction
Intermetallics & Composites
Advanced Biomaterials
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Biomaterials Concentration
4 required courses

2 MSE 4XX Electives

2 Technical Electives
Nanomaterials Concentration planned for
2010-2011 Catalog
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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

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For more information, contact:
Dr. Kevin Kit
kkit@utk.edu
510 Dougherty
974-7055
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