Ceramic Structural Composites The Most Advanced Structural Material Lance L Snead Presented at the International School on Fusion Reactor Technology Erice,

Ceramic Structural CompositesThe Most Advanced Structural Material

Lance L Snead

Presented at the International School on Fusion Reactor TechnologyErice, Italy

July 26 - August 1, 2004

MatrixFiber

Interphase

Composite -v- Monolithic Ceramics

fib

er

mat

rix

crack

crackarrest

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Composite materials, whether platelet, chopped fiber, or continuous fiber reinforced are superior“engineering”materials to monolithics:

• generally higher strength, especially in tension • higher Weibull modulus (more uniform failure) • much higher damage tolerance (fracture toughness)

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50

100

150

200

0 0.2 0.4 0.6 0.8 1

Str

en

gth

(M

Pa)

Displacement (mm)

Graphite

CarbonFiber

Composite

Monolithic

Strength (MPa)

Composite

Strength (MPa)

SiC 100 ± 50 220 ± 20

Graphite 107 ± 20 176 ± 20

Composite -v- Monolithic Ceramics

Toughness

MPa/m-1/2

Steel >50

Monolithic Ceramic 3

Platelet Reinforced Ceramic 6

Chopped Fiber Reinforced 10

Continuous Fiber Reinforced Ceramic

25-30


Composite Examples

Structural Composites in Aerospace Applications

• Thermal protection system for a re-entry space vehicle: Nose corn, leading edge, …

• Rocket engine: Extendable nozzle, aerospike engine, …• Scram-jet engine for a future space vehicle.

C/C with TBC/EBC is in commercial. SiC/SiC will be more attractive (e.g. Tyrannohex).

Weaving / 2D Cloth + Stitching

Successfully engine demonstrated at gas temperature 1573K (1998)

Exhaust Tail-cone

Weaving / 3-Axial Braiding

Successfully hot firing tested at gas temperature 2073K (1998)

SiC/SiC Thrust chamber

Carbon Fiber Reinforced Composites

TREK Madone 5.9

Carbon Fiber Composite

Glass Fiber Reinforced Composites

Ferrari 308 GT4

Glass Fiber Composite

Reinforced Concrete Composite

Steel reinforced “rebar” Carbon Fiber/epoxy rod

Reinforced Fired Adobe Composite

Inca city ~ 1500 AD Present Day


fib

er

mat

rix

crack

crackarrest

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Inca city ~ 1500 AD Present Day

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1.5

-0.5 0 0.5 1 1.5 2 2.5 3 3.5

Com

pre

ssiv

e S

tren

gth

(K

g/c

m2

)

% Straw or Grass

Ichu grass

Andes Straw

J. Vargas Data


Puye Cliff Dwelling

Anasaze Indians

1100-1580 AD

Fort Paramonga Chimu civilization ~1300 AD

Tel-Dan Arch~1600 BC

10000 bc 5000 bc 0 1000 1500 1600 1900 1940 1960 1980 1990 2000

10000 bc 5000 bc 0 1000 1500 1600 1900 1940 1960 1980 1990 2000

Date

Rel

ativ

e Im

po

rtan

ce METALS

POLYMERS/ELASTOMER

COMPOSITES

STRAW-BRICK HORSEHAIR PLASTER

GFREC/C

METALMATRIX

CERAMICMATRIX

WOODSKINFIBERS

GLUES

RUBBER

BAKELITENYLON POLYESTERS P.E. EPOXIES PMMA ACRYLICS

HIGH MODULUSPOLYMERS

HIGH TEMPERATUREPOLYMERS

GOLD COPPER BRONZE IRON CAST IRON STEELS ODS STEELS

LIGHT ALLOYS NEW SUPERALLOYS

SUPER ALLOYS GLASSY METALS

TITANIUM, ZIRCONIUM

etc. ALLOYS

PYROLITICCERAMICS

TOUGHENEDCERAMICS

CERAMICS/GLASSES

STONE FLINT POTTERY GLASS CEMENT REFRACTORIES PORTLAND CEMENT FUSED SILICA

CERMETS

Short History of Materials


Fusion Structural Composites

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500

600

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Yield Strength of Various Materials

Yie

ld S

tren

gth

(M

Pa)

Temperature (°C)

SuperalloyC/C Composite

Graphite

ZircaloyCarbon Steel

Stainless Steel

SiC/SiC

Yield Strength of Various Structural Materials

0 200 400 600 8001000120014001600Operating Temperature (°C)

C/C

SiC/SiC

Tungsten

Molybdenum

ODS Ferritic

F/M Steel

316 Stainless

Alloy 718

Questionable

Reasonable

Operating Range, Highly Irradiated Structural Materials


Carbon/Carbon Composites

- In widespread structural use- Manufacturing and design methods understood- Expensive…

Divertor Designs Using C/C Composites

Full-scale vertical target armored mock-up uses a pure Cu clad DS-Cu tube armored with saddle-block C/C and CVD-W armors. (Hitachi Ltd., Japan)

Pure Cu clad DS-Cu tube armored with C/C monoblocks. (Kawasaki Heavy Industries, Japan)

W

C/CC/C


Irradiation Performance of Carbon Fiber Composites

- Lifetime is limited- Tritium Retention Unavoidable

Graphite Under Irradiation

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0.1 1 10Norm

ali

zed

Th

erm

al

Con

du

cti

vit

y K

irr /

Ku

nir

r

Dose, 1022

n/cm2

1150 °C

600 °C

450 °C

300 °C

250 °C200 °C150 °C

920 °C

H451 Graphite

CFC’s Under Irradiation

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

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0 1 2 3 4 5

3D Balanced Weave

axis parallel toa set of fiber axes

Dose (dpa)

Dim

en

sion

al

Ch

an

ge (

%)

Pitch Fibers

PAN Fibers

-4

-3

-2

-1

0

1

0 1 2 3 4 5

Fiber AxisFiber Axis

1-D Fiber Composite (UFC)

axis parallel to fiber axes

Dose (dpa)

Dim

en

sion

al

Ch

an

ge (

%)

(HFIR , 600°C)

Composite allows “engineering” ofproperties such as dimensional change

samplesurface

bundleshrinkage

bundle swelling

gap500°C 800°C~ 10 dpa

fiber CFC’s Under Irradiation

bundleshrinkage

bundle swelling

gap

1

10

100

1000

200 400 600 800 1000 1200 1400

T-3

Ret

enti

on (

app

m)

Irradiation / T-3 Loading Temperature (C)

Non-irradiated, infinite charge time

Non-Irradiated1 hr Charge Time

High Quality Irradiated CFC (Causey, Snead)

Intermediate Quality Irradiated Graphite (Causey, Snead)

NRL IFE 2/2001

• T-3 attaches to basal plane edges and highly defected structure. More perfect material and/or high temperature allows less retention.

CFC’s Under Irradiation : Tritium Retention


SiC/SiC Composites

- Essentially no current structural application- Manufacturing and design methods immature

ARIES-I – First Blanket Design Using SiC/SiC

• Excellent safety & environmental characteristics (very low activation and very low afterheat).

• High performance due to high strength at high temperatures (>1000ºC).

ARIES-AT – Liquid Wall Blanket Concept (USA)

• Simple, low pressure design with SiC structure and self-cooled Pb-17Li breeder.• High Pb-17Li outlet temperature (~1100ºC) and high thermal efficiency of 58.5%.

- Max SiC/SiC temp.: 996ºC.- Max SiC/SiC-coolant (Pb-17Li) interface temp.: 900-940ºC.

• Simple manufacturing technique.• Very low afterheat.• Class C waste by a wide margin.

TAURO – SiC/SiC Blanket Design in EU

• Self-cooled Pb-17Li breeder and n multiplier.

• Pb-17Li inlet/outlet temperature (650/860ºC).

- Max SiC/SiC temp.: 995ºC.

- Max SiC/SiC-coolant (Pb-17Li) interface temp.: 915ºC.

• Simple manufacturing technique (based on joining of panels/tubes by brazing).

• The maximum shear in the joints is 60MPa.

• 6mm thickness as first wall to deal with thermo-mechanical loads.

• Brayton cycle thermal efficiency: >47%.


SiC/SiC Composites Under Irradiation

- May survive for life of machine- Thermal conductivity is likely less than assumed- Electrical conductivity appears not to be a problem

SiC Under Irradiation

QuickTime™ and aPhoto decompressor

are needed to see this picture.

• Irradiation-induced thermo-physical property changes (swelling, thermal conductivity, strength) saturate by a few dpa for T< 1000°C. Driven by simple defect clusters.

• Irradiation performance for T>1000°C is not well understood.

0.01

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10

0 200 400 600 800 1000 1200 1400 1600

Lin

ear

Swel

ling

(%

)

Irradiation Temperature (C)

void swelling regimepoint-defect swellingamorphization

Silicon Carbide Under Irradiation

• Irradiation-induced thermo-physical property changes (swelling, thermal conductivity, strength) saturate by a few dpa for T< 1000°C. Driven by simple defect clusters.

• Irradiation performance for T>1000°C is not well understood.

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Norm

ali

zed

Str

ess

(S ir

r/Save)

Cross Head Displacement (mm)

UnirradiatedStress (MPA), S

aveFiber type

292 (3 tests)Regular Nicalon™

359 (7 tests)Hi-Nicalon™

416 (2 tests)Type-S Nicalon™Type-S Nicalon

Composite

High NicalonComposite

Ceramic Grade Nicalon Composite10 mm

20 mm

2.3 x 6 x 30 mm

FCVI SiC Matrix, C-interphase, Plain Weave Composite~ 1 dpa, HFIR irradiation

ORNL / Kyoto U.

SiC/SiC Composites : Strength and Stability

Ceramic fiber 0.5 m

SiC-interlayerThin C-interlayer

SiC-interlayer

Bulk SiC

Until recently, SiC/SiC composites exhibited significant degradation inmechanical properties due to non-SiC impurities in fibers causing interfacial debonding.

Upon irradiation, if fibers densify, fiber/matrix interfaces debonds

-->strength degrades

300 nm

SiC fiber

SiC multilayersSiC multilayers

SiC/SiC Composites : Strength and Stability

Bend strength of irradiated“advanced” composites showno degradation up to 10 dpa

1st- and 2nd generation irradiated SiC/SiC composites show

large strength loss after doses >1 dpa

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0 200 400 600 800The

rmal

Con

duct

ivit

y (W

/m-K

)

Temperature (C)

CVD SiC

SiC/SiC Composites : Thermal Conductivity

CVD SiC Irradiated


K (T ) 1

1

Ku(T )

1

Kgb(T )

1

Kd 0

1

K rd

umklapp

boundaries

intrinsicdefects

radiationdefects

Ther

mal

Def

ect R

esis

tanc

e

0 200 400 600 800 1000

Temperature (C)

Specific Heat

Grain Boundary

Irradiation Defects

Grain Boundaries

Umklapp


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1000

0.1

1

10

0.001 0.01 0.1 1 10

Room

Tem

pera

ture

Th

erm

al

Con

du

cti

vit

y (

W/m

-K)

Sw

ellin

g (%

)

Neutron Damage (dpa)

800°C

600°C

200°C

200°C

600°C

400°C

800°C

Rohm Haas CVD SiC

IrradiationTemperature

300°C

300°C500°C

500°C

400°C

Data for an “ideal” SiC

Thermal conductivity reduction is due to simple vacancies and vacancy clusters. This is a strict material property which can not be improved upon.


K (T) 1

1

Ku(T)

1

Kgb (T)

1

Kd 0

1

Krd

Umklapp(phononScattering)

boundariesintrinsicdefects

radiationdefects

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100

150

200

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0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 0.5 1 1.5 2 2.5

200°C300°C400°C500°C600°C700°C800°C

1/Krd2001/Krd3001/Krd 4001/Krd 5001 krd 6001/krd7001/Krd 800

Therm

al Defect R

esistance, (1/Krd ) (m

-K/W

)

Roo

m T

empe

ratu

re T

herm

al C

ondu

ctiv

ity

(W/m

-K)

Irradiation-Induced Swelling (%)


K (T) 1

1

Ku(T)

1

Kgb (T)

1

Kd 0

1

Krd

Umklapp(phononScattering)

boundariesintrinsicdefects

radiationdefects

0.00

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0.10

0.15

0.20

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0.30

200 400 600 800 10001200

Present (340 W/m-K)

Price (72 W/m-K)

Price (50 W/m-K)

Senor (170 W/m-K)Youngblood (185 W/m-K)

Present (3.21 g/cc)

Price (3.20 g/cc)

Th

erm

al

Defe

ct

Resi

stan

ce (

m-K

/W)

Den

sity Ch

an

ge(%

)

Irradiation Temperature (°C)

Defect Resistance

Density

0

5

10

15

20

25

30

35 Maxim

um

Kth (W/m

-K)

0

0.5

1.0

Kth

1.5

x=goal

1

10

100

0 1 2 3 4 5Th

erm

al

Con

du

cti

vity

@ 2

0°C

(W

/m-K

)

Dose dpa

Tirr 800

Tirr 500

Tirr 300

Tirr 800

Tirr 500

Tirr 300

Rohm Haaas CVD SiCORNL Data

CVI SiC/Type-S (thru thickness)

Due to “interfaces” and cracks in SiC composite, thermal conductiivity will necessarily be less than ideal SiC.

Present materials are significanlty lower than ~15 W/m-K reactor study

goal.


* does not include prototyping or NDE evaluation.

Irradiation-Induced Property Change @ 1000°CMaterial Cost

$/KgLife(dpa)

Volume Strength(MPa)

Modulus ThermalConductivity

W/m-KSuperalloy 25 ~5 - - - -

CFC* ~200 10-15 -5% 150250 +20% 250180

SiC/SiC* ~400 >50? +1% 7575 -10% 5010

Composite Comparison for FISSION (at 1000°C)


SiC Matrix / Graphite Fiber Composites

- Now being used in NASA application- Manufacturing and design methods immature- May solve the dual problems of low thermal conductivity of SiC/SiC and high T-3 retention of C/C

TensileStrength (MPa)

SiC/SiC Composite (2-D lay-up) SiC/graphite Composite (2-D lay-up)

Argument #1: Strength (& toughness) as good or superior to SiC/SiC

Argument #2: Reduced tritium retention over best C/C’s

10

100

1000

104

0 20 40 60 80 100

UnirradiatedNeutron Irradiated

Hyd

rog

en

Solu

bil

ity

(ap

pm

)

Graphitic Perfection (%)

Tirr=600°CTload=1000°C

Reduced Basal

Plane Edge

Tritium retention, non-irradiated and irradiated, is highly dependent on graphite perfection.

K-1100 type fibers are nearly perfect.

SiC has very low tritium retention.

1

10

100

1000

104

0.001 0.01 0.1 1 10

N3M graphiteFMI-222 CFCMKC-1PH CFC

Tri

tiu

m R

ete

nti

on

(ap

pm

)

Radiation Damage (dpa)

Argument #2: Reduced tritium retention over best CFC’s

• By replacing the lower perfection matrix of CFC’s with SiC, SiC/graphite will have lower retention.

Tirr=200°CTload=1000°C

Intermediate QualityGraphite

High QualityGraphite Fiber Composite

Argument #3: Significant thermal conductivity enhancement

K (T ) 1

1

Ku (T )

1

Kgb(T )

1

Kd 0

1

Krd

DefectResistance

0.001

0.01

0.1

1

0.001 0.01 0.1 1 10

Th

erm

al

Defect R

estis

tan

ce (

m-K

/W)

dpa

Graphite CompositeIrradiated at 300°C

Graphite CompositeIrradiated at 60°C

CVD SiCIrradiated at 60 and 300°C

1/Krd Comp SiC-g

Engineered High Thermal Conductivity SiC/G Composite

• Matrix : CVI SiC , no interphase• Fibers : Z-direction either Amoco P55 or Thornel K-1100 fiber X-Y direction Amoco P-55 fiber. Total Volume Fraction 44%.• Architecture: Unbalanced 1-1-6 weave.

K1100 fiber

High TC

SiC Matrix / Graphite Fiber Composites• At fusion-relevant temp., SiC/g:--> conductivity exceeds present SiC/SiC--> conductivity exceeds SiC theoretical max.--> Low TC direction on order of SiC/SiC thermal conductivity (for this composite).

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300

350

400

0 200 400 600 800

Th

erm

al C

ond

uct

ivit

y (W

/m-K

)

Temperature (C)

Type-S Composite (transverse)

P55 Graphite/CVI SiC (high TC)

Morton CVD SiC

K1100 Graphite/CVI SiC (high TC)

ICFRM10 SiC/G

• At fusion-relevant temperature, SiC/g exceeds theoretical maximum of SiC/SiC

SiC Matrix / Graphite Fiber Composites

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200

250

300

350

400

0 200 400 600 800 1000 1200

Th

erm

al C

ond

uct

ivit

y (W

/m-K

)

Temperature (C)

CVD SiC/K1100 Non-Irradiated

CVD SiC/K1100 Irradiated

CVD SiCNon-Irradiated

CVD SiC Irradiated

Summary

• Fiber reinforced composites are arguably the oldest man-made structural material. However, because predictive design tool (codes) have been based on metallic design over the past century structural design with composites is currently impractical. Design is based on prototyping, not modeling….

• Carbon fiber composite manufacturing and application is fairly mature, however lifetime of composite structures is strictly defined to ~ 15 dpa, or a year in a fusion reactor. Tritium retention in CFC’s can be reduced, but never eliminated.

• SiC/SiC composite offer the possibility of lifetime components, but as-irradiated thermal conductivity will almost certainly be less than the 15 W/m-K assumed in present studies.

Questions ?

Questions ???

Fabrication of C/C Composites

“Graphitization”

carbon

graphite

Temperature

Carbon Fiber:• PAN (polyacrylonitrile) based carbon fiber

- Commercial use for general purpose.- Varieties: high strength, high modulus, long elongation, …

• Pitch based carbon fiber- High performance carbon fiber: Anisotropic, high graphitization.

Tensile strength: 2.3~4.0GPa, Tensile modulus: 400~900GPa- General purpose (low cost) carbon fiber: Isotropic microstructure.

Tensile strength: 0.6~1.0GPa, Tensile modulus: 30~60GPa

Carbon Matrix:• Chemical vapor deposition (CVD)• Impregnation and pyrolysis using resin or pitch.

Environmental Barrier Coating:Concern about high reactivity to oxidative products.• Boron based glasses (<1000ºC)• Silicon carbide (<1500ºC)

Key Characteristics of SiC(-based) Fibers

SiC FiberC/Si

AtomicRatio

OxygenContent(wt%)

TensileStrength(GPa)

TensileModulus(GPa)

Elongation(%)

Density(g/cm3)

Diameter(μm)

Tyranno SA Gr.3 1.07 <0.5 2.6 400 0.6 3 7

Hi-Nicalon Type-S 1.05 0.2 2.6 420 0.6 3.1 11

Hi-Nicalon 1.39 0.5 2.8 270 1.0 2.74 14

Documents

Ceramic Structural Composites The Most Advanced Structural Material Lance L Snead Presented at the International School on Fusion Reactor Technology Erice,