Transcript Synopsis - Oxford Materials

Total Design
is a systematic activity:
Identification of the market need → sale of product to
meet that need.
Product, Process, People, Organization, etc.
Design Core
Market Analysis
Specification
Concept Design
Detailed Design
Manufacturing
Sales
Product Design Specification (PDS)
Market
Assessment
Specification
Concept
Design
Detail
Design
Manufacture
Envelopes all stages of the design core
Sell
THE DESIGN CORE
The Design Core
Market
Assessment
Specification
DETAIL
DESIGN
Concept
Design
A vast subject. We will concentrate on:
Materials Selection
Detail
Design
Process Selection
Cost Breakdown
Manufacture
Sell
Materials Selection
Metals
and
Alloys
Steel-cord
tyres
Composites
Polymers
CFRP
GFRP
Filled polymers
Wire-reinforced cement
Cermets
MMCs
Ceramics
and
Glasses
Materials Properties
STRUCTURAL MATERIALS
FUNCTIONAL MATERIALS
Mechanical
tribology
fatigue
KIC
σy
UTS
E
Chemical
corrosion
oxidation
Physical
optical
magnetic
electrical
MATERIAL
Other
Thermal
α
K
H
Tm
TTransition
feel
look
Environmental
recycling
energy consumption
waste
Young’s Modulus, E
Material
E (GPa)
Material
E (GPa)
Material
Diamond
Tungsten carbide, WC
Cobalt/WC cermets
Borides of Ti, Zr, Hf
Silicon carbide, SiC
Boron
Tungsten
Alumina, Al2O3
Beryllia, BeO
Titanium carbide, TiC
Molybdenum and alloys
Tantalum carbide, TaC
Niobium carbide, TaC
Silicon nitride, Si3N4
Chromium
Beryllium and alloys
Magnesia, MgO
Cobalt and alloys
Zirconia, Zr0
Nickel and alloys
CFRP
Iron
Iron based superalloys
Steels
1000
450-650
400-530
500
450
441
406
390
380
379
320-365
Cast irons
Tantalum and alloys
Platinum
Uranium
Boron/epoxy composites
Copper and alloys
Mullite
Vanadium
Titanium and alloys
Palladium
Brasses and bronzes
Niobium and alloys
Silicon
Zirconium and alloys
Silica glass, SiO2 (quartz)
Zinc and alloys
Gold
Aluminium and alloys
Silver
Calcite (marble, limestone)
Soda glass
Granite
Tin and alloys
Concrete, cement
170-190
150-186
172
172
125
120-150
145
130
80-130
124
103-124
80-110
107
96
94
43-96
82
69-79
76
31-81
69
62
41-53
45-50
Magnesium and alloys
GFRP
Graphite
Alkyds
Common woods, ║ to grain
Lead and alloys
Ice, H2O
Melamines
Polyimides
Polyesters
Acrylics
Nylom
PMMA
Polystyrene
Epoxies
Polycarbonate
Common woods,  to grain
Polypropylene
Polyethylene (high density)
Polyethylene (low density)
Foamed polyurethane
Rubbers
PVC
Foamed polymers
289
200-289
250
200-284
160-241
130-234
70-200
196
193-214
196-207
E (GPa)
41-45
7-45
27
20
9-16
14
9.1
6-7
3-5
1-5
1.6-3.4
2-4
3.4
3-3.4
3
2.6
0.6-1
0.9
0.7
0.2
0.01-0.06
0.01-0.1
0.003-0.01
0.001-0.01
Yield Strength (σy) & UTS (σTS)
Material
Pressure-vessel steels
Low alloy steels
Molybdenum and alloys
Tungsten
Nickel alloys
Carbon steels
Titanium and alloys
Tantalum and alloys
CFRPs
Cobalt/WC cermets
Cast irons
Copper alloys
Concrete (steel reinforced)
Stainless steel (austenitic)
Aluminium alloys
Brasses and bronzes
Stainless steels (ferritic)
Zinc alloys
Zirconium alloys
Mild steel
GFRPs
Magnesium alloys
Beryllium and alloys
PMMA
σy
(MPa)
σTS
(MPa)
1500-1900
500-1980
560-1450
1000
200-1600
260-1300
180-1320
330-1090
--400-900
220-1030
60-960
--286-500
100-627
70-640
240-400
160-421
100-365
220
--80-300
34-276
60-110
1500-2000
680-2400
665-1650
1510
400-2000
500-1880
300-1400
400-1100
640-670
900
400-1200
250-1000
410
760-1280
300-700
230-890
500-800
200-500
240-440
430
100-300
125-380
380-620
110
Material
σy
(MPa)
σTS
(MPa)
Ice, H2O
Polyimides
Nickel
Nylons
Epoxies
Copper
Silver
ABS/polycarbonate
Polystyrene
Iron
Pure ductile metals
Acrylic/PVC
Aluminium
Gold
Lead and alloys
Polyurethane
Polypropylene
Tin and alloys
Polyethylene (high density)
Concrete (non-reinf’d, comp’n)
Polyethylene (low density)
Ultrapure fcc metals
Foamed polymers (rigid)
Polyurethane foam
85
52-90
70
49-87
30-100
60
55
55
34-70
50
20-80
45-48
40
40
11-55
26-31
19-36
7-45
20-30
20-30
6-20
1-10
0.2-10
1
----400
100
30-120
400
300
60
40-70
200
200-400
--200
220
14-70
58
33-36
14-60
37
--20
200-400
0.2-10
1
Density, ρ
Material
Osmium
Platinum
Tungsten and alloys
Gold
Uranium
Tungsten carbide, WC
Tantalum and alloys
Molybdenum and alloys
Cobalt/WC cermets
Lead and alloys
Silver
Niobium and alloys
Nickel and alloys
Cobalt and alloys
Copper and alloys
Brasses and bronzes
Iron
Iron-based superalloys
Steels
Tin and alloys
Cast irons
ρ
(Mgm-3)
22.7
21.4
13.4-19.6
19.3
18.9
14.0-17.0
16.6-16.9
10.0-13.7
11.0-12.5
10.7-11.3
10.5
7.9-10.5
7.8-9.2
8.1-9.1
7.5-9.0
7.2-8.9
7.9
7.9-8.3
7.5-8.1
7.3-8.0
6.9-7.8
Material
ρ
(Mgm-3)
Titanium carbide, TiC
Zinc and alloys
Chromium
Zirconium carbide, ZrC
Zirconium and alloys
Titanium and alloys
Alumina, Al2O3
Magnesia, MgO
Silicon carbide, SiC
Silicon nitride, Si3N4
Mullite
Beryllia, BeO
Calcite (marble, limestone)
Aluminium and alloys
Silica glass, SiO2 (quartz)
Soda glass
Concrete/cement
GFRPs
Carbon fibres
PTFE
Boron/epoxy composites
7.2
5.2-7.2
7.2
6.6
6.6
4.3-5.1
3.9
3.5
2.5-3.2
3.2
3.2
3.0
2.7
2.6-2.9
2.6
2.5
2.4-2.5
1.4-2.2
2.2
2.3
2.0
Material
Beryllium and alloys
Graphite (high strength)
CFRPs
PVC
Polyesters
Polyimides
Epoxies
Polycarbonate
Polyurethane
PMMA
Nylon
Polystyrene
Polyethylene (high density)
Ice, H2O
Polyethylene (low density)
Polypropylene
Rubber
Common woods
Foamed polymers
Foamed polyurethane
ρ
(Mgm-3)
1.8-2.1
1.8
1.5-1.6
1.3-1.6
1.1-1.5
1.4
1.1-1.4
1.2-1.3
1.1-1.3
1.2
1.1-1.2
1.0-1.1
0.94-0.97
0.92
0.91
0.88-0.91
0.83-0.91
0.4-0.8
0.01-0.6
0.06-0.2
Specific Properties
Material
Cobalt/WC cermets
Beryllium and alloys
Low-alloy steels
CFRP
Aluminium alloys
Common woods, ║ to grain
Lead and alloys
Polypropylene
Foamed polymers
E
Cobalt/WC cermets
Beryllium and alloys
Low-alloy steels
CFRP
Aluminium alloys
Common woods, ║ to grain
Lead and alloys
Polypropylene
Foamed polymers
E
(GPa)
σ
(MPa)
ρ
(Mgm-3)
E/ρmean
(106 m2s-2)
σ/ρmean
(103 m2s-2)
400-530
200-289
200-207
70-200
69-79
9-16
14
0.9
0.001-0.1
400-900
34-276
500-1980
640-670
100-627
35-55
11-55
19-36
0.2-10
11-12.5
1.8-2.1
7.8
1.5-1.6
2.6-2.9
0.4-0.6
10.7-11.3
0.88-0.91
0.01-0.6
34-45
103-148
26-27
45-129
25-45
15-27
1.3
1.0
0.003-0.03
34-77
17-141
64-253
413-432
36-228
58-92
1.0-5.0
21-40
0.66-33
E/ρmean
Beryllium and alloys
CFRP
Cobalt/WC cermets
Aluminium alloys
Low-alloy steels
Common woods, ║ to grain
Lead and alloys
Polypropylene
Foamed polymers
σ
Low-alloy steels
Cobalt/WC cermets
CFRP
Aluminium alloys
Beryllium and alloys
Common woods, ║ to grain
Lead and alloys
Polypropylene
Foamed polymers
σ/ρmean
CFRP
Low-alloy steels
Aluminium alloys
Beryllium and alloys
Common woods, ║ to grain
Cobalt/WC cermets
Polypropylene
Lead and alloys
Foamed polymers
Materials Selection without Shape
Generic materials selection
Examples
• Problem statement
• Model
• Function, Objective,
Constraints
• Selection
•
•
•
•
•
•
•
Oars
Mirrors for large telescopes
Low cost building materials
Flywheels
Springs
Safe pressure vessels
Precision devices
Generic Materials Selection
p: Performance of component;
f(F,G,M)
F: Functional requirement, e.g. withstanding a force
G:Geometry, e.g. diameter, length etc.
M:Materials properties, e.g. E, KIC, ρ
Separable function if:
P = f1(F) · f2(G) · f3(M)
TASK: Maximize f3(M) where M is the “performance index”
Procedure for Deriving “M”
(a)
Identify the attribute to be maximized or minimized (weight, cost, energy, stiffness,
strength, safety, environmental damage, etc.).
(b)
Develop an equation for this attribute in terms of the functional requirements, the
geometry, and the material properties ( the objective function).
(c)
Identify the free (unspecified) variables.
(d)
Identify the constraints; rank them in order of importance.
(e)
Develop equations for the constraints (no yield, no fracture, no buckling, maximum
heat capacity, cost below target, etc.).
(f)
Substitute for the free variables from the constraints into the objective function.
(g)
Group the variables into three groups: functional requirements, F, geometry, G, and
materials properties, M.
(h)
Read off the performance index, expressed as a quantity, M, to be maximized.
(i)
Note that a full solution is not necessary in order to identify the material property
group.
The Materials Selection Map
MATERIALS PROPERTY 2
1000
Guidelines for
M = Prop2/Prop1
Search
Region
100
10
M = 40
1
0.1
1
10
MATERIALS PROPERTY 1
100
Example I: A light strong tie
Mass :
m  AL
A
Stress :  f 
m
F

m
L
F FL

A
m
L

Search
Region

f
M = 100Nm/g
f1(F)
f2(G)
f3(M)
So, to minimize mass m,
maximise M 
f

Example II: A light stiff column (circular)
Fbuck ling
n 2EI

L2
I  r 4 / 4  A2 / 4
m  AL
Fbuckling
n 2EA2 nEm 2


2
4L
4L4  2
L4 
m2 F

n
E
f1(F)·f2(G)·f3(M)
So, to minimize mass m,
maximise M 
E 1/ 2

Search
Region
Example III: Pressure Vessel
Light weight cylindrical
vessel of fixed radius

pR
, m   2RLdR
dR
Search
Region
m
dR 
 2RL

pR 2RL
m
 m  p  2R 2L 


f1(F)·f2(G)·f3(M)
So, to minimize mass m,
maximise M 
f

Performance Indices: Elastic Design
Component and design goal
Maximise
Springs: Specified energy storage, volume to be minimized
σf2/E
Springs: Specified energy storage, mass to be minimized
σf2/Eρ
Elastic hinges: Radius of bend to be minimized
σf/E
Knife edges, pivots: Minimum contact area, maximum bearing load
σf3/E2 & E
Compression seals and gaskets: Maximum contact area with specified
maximum contact pressure
σf/E & 1/σf
Diaphragms: Maximum deflection under specified pressure of force
σf3/2/E
Rotating drives, centrifuges: Maximum angular velocity, radius specified,
wall thickness free
σf/ρ
Ties, columns: Maximum longitudinal vibration frequencies
E/ρ
Beams: Maximum flexural vibration frequencies
E1/2/ρ
Plates: Maximum flexural vibrationfrequencies
E1/3/ρ
Ties, columns, beams, plates: Maximum self-damping
η
Note: σf = failure strength; E = Young’s modulus; ρ = density; η = loss coefficient
Performance Indices: Min. Weight
Component and loading
Stiffness:
Maximize
Strength:
Maximize
E/ρ
σf/ρ
Torsion bar or tube: Torque, stiffness, length specified, section area free
G1/2/ρ
σf2/3/ρ
Beam: Loaded externally or by self-weight in bending; stiffness, length specified,
section area free
E1/2/ρ
σf2/3/ρ
Column (compression strut): Failure by elastic buckling or plastic compression;
collapse load and length specified, section area free
E1/2/ρ
σf/ρ
Plate: Loaded externally or by self-weight in bending; stiffness, length, width
specified, thickness free
E1/3/ρ
σf1/2/ρ
Plate: Loaded in-plane; failure by elastic buckling or plastic compression; collapse
load, length and width specified, thickness free
E1/3/ρ
σf/ρ
-
σf/ρ
E/ρ
σf/ρ
E/(1-ν)ρ
σf/ρ
Tie (tensile strut): Load, stiffness, length specified, section area free
Rotating disks, flywheels: Energy storage specified
Cylinder with internal pressure: Elastic distortion, pressure and radius
specified, wall thickness free
Spherical shell with internal pressure: Elastic distortion, pressure and radius
specified, wall thickness free
Note: σf = failure strength; E = Young’s modulus; G = shear modulus; ρ = density
Performance Indices: Min. Weight
fixed:
Maximize
≈ min section:
Maximize
KIC/ρ
KIC4/3/ρ
Torsion bar or tube: Torque, length specified, section area free
KIC2/3/ρ
KIC4/5/ρ
Beam: Loaded externally or by self-weight in bending; stiffness,
length specified, section area free
KIC2/3/ρ
KIC4/5/ρ
Column (compression strut): Failure by elastic buckling or plastic
compression; collapse load and length specified, section area free
KIC2/3/ρ
KIC4/5/ρ
Plate: Loaded externally or by self-weight in bending; load, length,
width specified, thickness free
KIC1/2/ρ
KIC2/3/ρ
Plate: Loaded in-plane in tension; collapse load, length and width
specified, thickness free
KIC/ρ
KIC2/ρ
Rotating disks, flywheels: Energy storage specified
KIC/ρ
KIC/ρ
Cylinder with internal pressure: Elastic distortion, pressure and
radius specified, wall thickness free
KIC/ρ
KIC2/ρ
KIC/(1-ν)ρ
KIC2/(1-ν)ρ
Component and loading
Crack length
Tie (tensile strut): Load, length specified, section area free
Spherical shell with internal pressure: Elastic distortion,
pressure and radius specified, wall thickness free
Note: KIC = fracture toughness ρ = density
Nomenclature
a,R,r
aC
A
C,C1,n
CR
E
F
Fbuckling
g
G
I
J
K
KIC
L
m
M
p
Q
SB
ST
t
Radius
Half crack length
Cross-sectional area
Constant dependent upon loading system
Relative cost
Young’s modulus
Force
Critical force for the onset of buckling
Acceleration due to gravity
Shear modulus
Second moment of area
Polar moment
Resistance to twisting of section
Fracture toughness
Beam, shaft etc. length
Mass
Performance index; Bending moment
Pressure
Section modulus in torsion
Bending stiffness
Torsional stiffness
Thickness
T
To
U
V
ym
WV
x
Z
α
δ
ε
η
θ
λ
ν
ρ
σ
σf

φ
ψ
ω
Temperature; Torque
Initial temperature
Kinetic energy
Volume
Distance from neutral axis to highest stressed surface
Stored energy
Distance
Section modulus in bending
Linear coefficient of thermal expansion
Deflection
Strain
Loss coefficient
Angle of twist
Thermal conductivity
Poisson’s ratio
Density
Stress
Failure stress
Maximum surface shear stress
Macro-shape factor
Micro-shape factor
Angular velocity
Materials for Large Telescopes
m  a2t
Mass :
3mga 2

4Et 3
Deflection :
1/ 2
DESIGN REQUIREMENTS
Function
Precision mirror
Objective
Minimize mass
Constraints
(a)
(b)
(c)
Radius a specified
Must not distort more
than δ under its own
weight
High dimensional
stability: no creep, no
moisture absorbtion, low
thermal expansion

 3g 
m 
 4 
  
 a   1/ 3 
E 
3/2
2
f1(F)·f2(G)·f3(M)
So, to minimize mass m,
maximise
M
E 1/ 3

Materials for Large Telescopes
Search
Region
M=2
(GPa)1/3m3/Mg
M
E 1/ 3

Material
M
Comment
Steel
Concrete
0.7
1.4
Al alloys
Glass
GFRP
Mg alloys
1.5
1.6
1.7
2.1
Wood
Beryllium
3.6
3.65
Foamed polystyrene
3.9
CFRP
4.3
Very heavy. The original choice.
Heavy. Creep, thermal distortion
problems.
Heavy. High thermal expansion.
The present choice.
Not dimensionally stable enough.
Lighter than glass, but high thermal
expansion.
Dimensionally unstable.
Very expensive. Good for small
mirrors.
Very light, but not dimensionally
stable.
Very light, but not dimensionally
stable: use for radio telescopes.
Materials for Oars
Mass :
m  r 2  AL
Stiffness :
S
F


Second
moment of area:
C1EI
L3
I
r 4
4

DESIGN REQUIREMENTS
1/ 2
Function
Light, stiff beam
Objective
Minimize mass
Constraints
(a) Length specified
(b) Bending stiffness
specified
(c) Toughness > 1 kJ/m2
(d) Cost <$100/kg

 4F 

m  
 C1 
 L5 / 2 

E 1/ 2
So, to minimize mass m,
maximise M 
E 1/ 2

A2

Materials for Oars
M
E 1/ 2
Search
Region

Material
M=6
(GPa)1/2m3/Mg
M
Woods
5-8
CFRP
4-8
GFRP
2-3.5
Ceramics
4-8
Comment
Cheap, traditional, but with
natural variability.
As good as wood, more control
of properties.
Cheaper than CFRP, but lower
M, thus heavier.
Good M, but toughness low and
cost high.
Materials for Buildings
Floor Beam
F
b
y
σ=σy
DESIGN REQUIREMENTS
Function
Floor beams
Objective
Minimize cost
Constraints
(a) Length specified
(b) Stiffness: must not
deflect too much
under design loads
(c) Strength: must not fail
under design loads
E 1/ 2
M1 
 CR
 y2 / 3
M2 
 CR
b
Materials for Buildings
Search
Region
Search
Region
M1 = 1.6
M2 = 6.8
Materials for Safe Pressure Vessels
DESIGN REQUIREMENTS
Yield before break

CK IC
,
aC
K 
aC  C 2  IC 
 f 
M1 
K IC
f
Function
Pressure vessel =contain
pressure p
Objective
Maximum safety
Constraints
(a) Must yield before break
(b) Must leak before break
(c) Wall thickness small to
reduce mass and cost
Leak before break
Minimum strength
pR
pR
, t
2t
2 f
M3   f
2
 
t
CK IC
 
2
t / 2
C 2pR K IC2

K IC2
M2 
4
f
aC 
f
Materials for Safe Pressure Vessels
Search
Region
M1 
M1 = 0.6 m1/2
M3 = 100 MPa
K IC
f
M2 
K IC2
f
M3   f
Material
M1
(m1/2)
M3
(MPa)
Comment
Tough steels
Tough Cu alloys
Tough Al alloys
>0.6
>0.6
>0.6
300
120
80
Standard.
OFHC Cu.
1xxx & 3xxx
Ti-alloys
High strength Al
alloys
GFRP/CFRP
0.2
0.1
0.1
700
500
500
High strength,
but low safety
margin. Good
for light
vessels.
Materials for Springs
σ
σf
Energy
Stored
σf/E
Tie :
DESIGN REQUIREMENTS
Function
Elastic spring
Torsion :
Objective
(a) Maximum stored elastic energy
per unit volume
(b) Maximum stored elastic energy
per unit mass
Leaf :
Constraints
(a) No failure by yield, fracture or
fatigue, i.e. σ <σf everywhere
(b) Adequate toughness: GC>1
kJ/m2
M1 
 f2
E
1  f2
WV 
2 E
1  f2
WV 
3 E
1  f2
WV 
4 E
 f2
M2 
E
ε
Materials for Springs
M1 
Search
Region
M1 = 6 MJ/m3
 f2
E
Material
M1
(MJ/m3)
Comment
Ceramics
Spring steel
10-100
15-25
Ti alloys
CFRP
15-20
15-20
GFRP
Glass (fibres)
10-12
30-60
Nylon
1.5-2.5
Rubber
20-50
Brittle in tension; good only in compression.
The traditional choice: easily formed and heat
treated.
Expensive, corrosion resistant.
Comparable in performance with steel;
expensive.
Almost as good as CFRP and much cheaper.
Brittle in torsion, but excellent if protected
against damage; very low loss factor.
The least good; but cheap and easily shaped,
but high loss factor.
Better than spring steel, but high loss factor.
Materials for Springs
 f2
M2 
E
Search
Region
Material
M2
(kJ/kg)
Comment
Ceramics
Spring steel
Ti alloys
5-40
2-3
2-3
CFRP
GFRP
Glass (fibres)
4-8
3-5
10-30
Brittle in tension; good only in compression.
Poor because of high density.
Better than steel; corrosion resistant,
expensive.
Better than steel; expensive.
Better than steel; less expensive than CFRP.
Brittle in torsion, but excellent if protected
against damage; very low loss factor.
On a weight basis, wood makes good
springs.
As good as steel; but has a high loss factor.
Outstanding;10 times better than steel, but
has a high loss factor.
Wood
M2 = 2 kJ/kg
Nylon
Rubber
1-2
1.5-2
20-50
Materials for Flywheels
Kinetic energy: U  J 2 / 2
Polar moment of inertia: J  R 4t / 2
Mass: m  R 2t
Stress:   R 2 / 2
DESIGN REQUIREMENTS
DESIGN REQUIREMENTS
Function
Flywheel for energy storage
Function
Flywheel for child’s toy
Objective
Maximize kinetic energy per
unit mass
Objective
Maximize kinetic energy per
unit volume
Constraints
(a) Must not burst
(b) Adequate toughness to
give crack tolerance
Constraints
Outer radius fixed
Materials for Flywheels
Maximizing energy/mass
U
1 2
J ,
2
U 

4

2
R 4t
R 4t 2
U 1 2 2
 R
m 4
U  2 f
 3   2

 
 R 

8
m
3






m  R 2t
 max
J

M1 
f

Maximizing energy/volume
U 1
 R 2 2
V 4
M2  
Search
Region
M1 = 100 kJ/kg
Materials for Flywheels
Material
Ceramics
M
(kJ/kg)
200-2000
Comment
Brittle and weak in tension – eliminate.
(Compression only)
Composites:
CFRP
GFRP
Beryllium
High strength steel
High strength Al alloys
High strength Mg alloys
Ti alloys
Pb alloys
Cast iron
200-500
100-400
300
100-200
100-200
100-200
100-200
3
8-10
The best performance – a good choice.
Almost as good as CFRP and cheaper – an excellent choice.
Good, but expensive, difficult to work and toxic.
All about equal performance. Steel and Al alloys cheaper
than Mg and Ti alloys.
High density makes these a good (and traditional) selection
when performance is velocity limited, not strength limited.
Materials for Precision Devices
Heat flow :
q  (dT / dx )
Thermal strain :    (To  T )

DESIGN REQUIREMENTS
Function
Force loop (frame)
Objective
Maximize positional
accuracy (minimize
distortion)
Constraints
(a) Must tolerate heat flux
(b) Must tolerate vibration
(d / dx )   (dT / dx )  q / 
M1 
M2 


E 1/ 2

Materials for Precision Devices

M1 

Al
Ag
Cu
Au
Be Mo
W
SiC
Si

Material
M1
M2
Comment
Diamond
5x108
8.6
Oustanding M1 and M2;
expensive
Si
4x107
6.0
Excellent M1 and M2; cheap
SiC
2x107
6.2
Excellent M1 and M2; potentially
cheap
Be
107
9
Less good than Si or SiC
Al
107
3.1
Poor M1, but very cheap
Ag
Cu
Au
2x107
2x107
2x107
1.0
1.3
0.6
High density gives poor M2
W
Mo
Invar
3x107
2x107
3x107
1.1
1.3
1.4
Better than Cu, Ag or Au, but
less good than Si, SiC or
diamond
Diamond
Search
Region
M1 = 107 W/m
M2 
E 1/ 2