fabrication of sic/sicf composite
DESCRIPTION
This paper was presented on the ISASC 2008 (International symposium on new frontier of advanced Si-based ceramics and compositesTRANSCRIPT
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FABRICATION OF SiC/SiCf COMPOSITE BY VACUUM INFILTRATION AND
HOT PRESSINGParlindungan Yonathan1, Jong-Hyun Lee1, Dang-Hyok Yoon1,
Weon-Ju Kim2 and Ji-Yeon Park2
1School of Materials Science and Engineering, Yeungnam University2Nuclear Materials Research Division, KAERI, Korea
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Presentation OutlineBackground
SiC/SiCf applications and advantagesFusion reactors applications and issuesMain Goal
MaterialsProcessCompositionDesignResult
SiC/SiCf ExperimentConclusion
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Background
4
SiC/SiCf Advantages
High specific strengthGood high-temperature propertiesGood fracture resistanceGood thermal conductivityCorrosion and wear resistanceLow induced radioactivity under nuclear environments
5
SiC/SiCf Applications
6
Fusion Reactors
First WallBe, Be-alloy W, W-alloy
SiC/SiCf,C/C
He bubbles
Fusion reactor blanket concept:
• TAURO, European Union (SiC/SiCf)
• ARIES-AT, US (SiC/SiCf)
• DREAM, Japan (Be-Li2O-SiC)
*Fusion technology institute, University Wisconsin
ARIES-AT vertical cross-section
7Permeability issue in SiC/SiCf
Bombardment of high energetic neutrons in to composite surface
Bubbles formation on the surface or blistering
0.86Å
Point defect behavior in ceramics
He and H atoms will move to a porous site, vacancy cluster, and grain boundary to start causing delamination issue
* J.H Kim, Y.D Kwon, Parlindungan Yonathan, I. Hidayat, “The energetic of He and H atoms in the irradiated β-SiC: abinitio approach”
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Main GoalTo achieve a high density SiC/SiCf composite by maximizing SiC slurry infiltration into SiC woven fiber and finally to attain high structural strength composite materialProcess development high density composite material:
Milling processInfiltration methodSlurry compositionTape casting
Evaluation of material performanceMaterial characteristics and morphologyMechanical properties
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Materials
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SiC powder
Average particle size: 52nm(NanoAmor), 30nm(Marketech)Fine & spherical β-SiCBET: 80 m2/g (NanoAmor), 109 m2/g (Marketech)Surface is covered with SiO2 layer thinner than 2nm
β-SiC, Marketech
1.7nm
β-SiC, NanoAmor
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SiC Woven fiber
2D woven fiber
PyC coated by KAERI
PyC coated design was based on CVI-SiC/SiCfcomposite process
Top view Cross-section view Pyrolitic carbon-coated fiber
3.1Mass density (g/cm3)
2500Tensile strength (MPa)
1600Number of filaments/yarn
7.5Diameter (mm)
(C/Si) 1.08, Al 0.005 Atomic composition
Tyranno-SA Grade-3 Properties
TyrannoTM-SA Grade-3 FiberUbe Industries, Ltd., Tokyo, Japan
(220nm)
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Sintering Additives
Magnesium Oxide (MgO)Alumina Oxide (Al2O3) Yttrium (III) Oxide (Y2O3)
Sintering additives facilitate the densification of SiC due to its highly covalent bond structureAl2O3/Y2O3/MgO = (0.64/0.26/0.1) wt%*Liquid phase assisted sintering
* KY Lim, DH Jang, YW Kim, JY Park, DS Park," Effect of the processing parameters on the densification and strength of 2D SiC fiber-SiC matrix composites fabricated by slurry infiltration and stacking process
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Process
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Process focus
Milling (dispersion)Solid volume fraction in green bodyRate of infiltration and densificationSinterability (pressure, temperature)
Effective infiltrationControllable infiltration
Infiltration
15Ball milling vs. High Energy Milling
@
The most conventional mechanical milling2–200 mm spherical or cylindrical ballsRotation under 200 rpm
Recently introduced (MiniCer, Netzsch)0.01 – 0.8 mm ZrO2 beadsRotation up to 4200rpmVery effective in milling
High energy millBall mill
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0 20 40 60 80 100 120
0
3000
6000
9000
12000
15000
0 20 40 60 80 100 120
Milling time (hr)
Visc
osity
(mPa
.s)
High energy milling
Ball milling
Milling time (min)
Why HEM
212.
11.1
rlA
φφσ
−=
Rumpf’s Equation:
n
rr
tt
⎟⎟⎠
⎞⎜⎜⎝
⎛=
2
1
2
1
Herring’s scalling laws:
All proposed mechanisms of sintering and densification of ceramic powder compacts agree that the particle size is one of the most important parameters in the rate of progress of these processes.
At constant temp
* Nono Darsono a, Dang-Hyok Yoon a,*, Jaemyung Kim b, “Milling and dispersion of multi-walled carbon nanotubes in texanol”
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Vacuum Infiltration
Enhance the infiltration by vacuum absorption forceEnhance the composite density in fiber
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Vacuum InfiltrationThe slurry is infiltrated as the vacuum pressure progressively released to return to surrounding pressure, thereby causing the slurry to be forced through the fiber pores.Advantages:
Using vacuum force to help infiltration processInfiltration can be controlled by altering the vacuum pressure and release of vacuum time.
Vacuum pressure 0.1PaPumping speed 120L/min
SiC Slurry
SiC Fiber
Vacuum onVacuum release
19Vacuum Infiltrated fiber - SEM
Top viewC
ross-section view
Normal infiltration (dipping) Vacuum infiltration
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Composition
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Composition
Two types of slurryInfiltration slurry Tape casting (binder 40% wt% wrt. powder)
Two composition variablesSintering additives (2/6/10 wt% wrt. powder)Binder (PVB B-98, 0/5/10/45% wrt. powder)
22Effect of sintering additives
99.89%3.19810NanoAmor
99.16%3.1746NanoAmor
79.02%2.5292NanoAmor
99.55%3.18710Marketech
99.29%3.1786Marketech
69.21%2.2152Marketech
Density (%)Density (g/cm3)
Sintering additives (% w.r.tpowder)Powder Type
Sintering additives
High Energy Milling
Drying
Solvent (Ethanol)
High Energy Milling
Hot Pressing
Density(Archimedes)
SEM
TEM SEM
Drying
Sintering additives
SiCPowder
Bending test (4-point)
2 4 6 8 100
100
200
300
400
500
0
20
40
60
80
100
Marketech Density
Rel
ativ
e D
ensi
ty (%
)
Additive (wt%)
Flexural Strength (MPa)
Marketech Flexural Strength
Relative density & Flexural strength
Nanostructure Density
Nanostructure Flexural Strength
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Effect of binder
0%NanoAmor4
5%NanoAmor3
10%NanoAmor2
45%NanoAmor1
Binder percentage (w.r.t. powder)Powder TypeNo.
Vacuum infiltration
High energy milling
Binder solution
Cryo-fracture
SEM
Drying
Density(Archimedes)
SEM
Binder burn-out
Hot Pressing
Bending test(4-point)
-5 0 5 10 15 20 25 30 35 40 45 500
10
20
30
40
50
Sintering additives 6%Shear Rate at 42.24/sec
Infiltration slurry viscosity (β−SiC NanoAmor)
Visc
osity
(cP)
Binder (% wrt powder)
0 5 10 45
24SEM pictures of infiltrated fibers after binder burn-out
Fiber cross-section45% binder
Fiber cross-section10% binder
Fiber cross-section5% binder
Fiber cross-section0% binder
Top-view45% binder
Top-view10% binder
Top-view5% binder
Top-view0% binder
25SEM pictures of hot-pressed infiltrated fiber
Fiber cross-section45% binder
Fiber cross-section10% binder
Fiber cross-section5% binder
Fiber cross-section0% binder
Cross-section view45% binder
Cross-section view10% binder
Cross-section view5% binder
Cross-section view0% binder
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0% 5% 10% 45%
2.4
2.5
2.6
2.7
2.8 Infiltrated fiber hot-pressed density
Density Percentage
Binder content (%)
Den
sity
(g/
cm3 )
80
90 Measured density/True D
ensity (%)
Density of infiltrated fiber
161.43131121.52117.6Flexural Strength (MPa)87.35%83.56%80.83%80.42%Percentage density2.7082.59052.5057142.493143Density45%10%5%0%Binder Composition
0% 5% 10% 45%50
75
1000% 5% 10% 45%
100
150
200
Flexural Strength (MPa)
Relative density & Flexural strength of SiC/SiCf
Rel
ativ
e D
ensi
ty (%
)
Additive (wt%)
Density
FlexuralStrength
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Composite design
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Composite structureComposite formed by stacking the SiC green sheet and the infiltrated SiC fibersBinder burn-out at 4000C for 2-hours at 1oC/minHot pressed at 1750oC, 20MPa, 3-hours
SiC infiltrated fiber (NanoAmor)
SiC infiltrated fiber
(Marketech)
Green tape (NanoAmor)
Green tape (Marketech)
SiC green tape
Infiltrated SiCfiber with SiCslurry
SiC/SiCf composite [0o/45o]62-72% fiber volume fraction
Hot pressing
5cm20 infiltrated fibers and
tapes
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Effect of green tape
Factors:Slurry compositionDispersionZeta potentialViscosity
vacuum infiltration & stack with SiCTapes
HEM (High energy milling)
Binder solution
Cryo-fracture
SEM
Drying
Density(Archimedes)
SEM
Binder burn-out
Sintering (Hot Pressing)
Bending test(4-point)
Tape casting
DISPERSION STABILITY AND ITS EFFECT ON TAPE CASTING OF SOLVENT-BASED SiC SLURRY Jong-Hyun Lee, Parlindungan Yonathan, Dang-Hyok Yoon, Weon-Ju Kim* and Ji-Yeon Park* (Yeungnam University, Korea, * KAERI, Daejeon, Korea)
30Sintered SiC/SiCf
Nano-tape Nano Marketech60
80
100
100
200
300Relative density & Flexural strength of SiC/SiCf
Flexural Strength (MPa)
Rel
ativ
e D
ensi
ty (%
)
Powder type
Sample 1 (Nano-tape)
Sample 2 (Nano)
Sample 3 (Mark-tape)80-90%90-95%98.78%Percent density (%)2.5-2.82.9-3.03.161Density (g/cm3)
CVI-PiPOther Hot pressing
reported value
Vacuum infiltration & Hot pressing
31Mechanical 4point bending test
Sample 1 (Nano-tape)
Sample 2 (Nano)
Sample 3 (Marketech)
NanoAmor(tape)
NanoAmor(no tape)
Marketech(tape)
32Sintered fracture cross-section
NanoAmor+Tape(Before bending test)
NanoAmor+Tape(After bending test)
NanoAmor(After bending test)
Marketech+Tape(After bending test)
NanoAmor+Tape(Before bending test)
NanoAmor+Tape(Before bending test)
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XRD result
20 30 40 50 60 70 80
β−SiC phase α−SiC phase
XRD result of SiC/SiCf composite
NanoSample 2
MarketechSample 3
Inte
nsity
(a.u
.)
2θ
NanotapeSample 1
The phase structure were changed for both nano powder, however phase change were not observed for marketechpowder
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Conclusion• High density of SiC/SiCf was achieved at 3.161g/cm3
(98.78%) by vacuum infiltration and hot pressing process.• Flexural strength of 230MPa was achieved with a brittle
fracture mode showing very little fiber pull out. • Phase changed was observed after hot pressing at 1750oC-
20MPa-3hours, showing both alpha and beta-SiC phase in the composite.
• SiC tape improved the sintered density and strength in the SiC/SiCf composite.
• Slurry formulation including sintering additives plays an important role in vacuum infiltration and hot pressing process.
• More intensive experiment on SiC/SiCf interface to improve the composite strength.
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This project is financial supports by:The Ministry of Knowledge Economy through a Materials &
Components Technology R&D ProgramHighly appreciated
Acknowledgement