Implementation Challenges for Sintered Silicon Carbide ... · MS&T 2011, Columbus, OH, Oct....
Transcript of Implementation Challenges for Sintered Silicon Carbide ... · MS&T 2011, Columbus, OH, Oct....
Invited Lecture International Symposium in honor of Prof. K.K. Chawla
MS&T 2011, Columbus, OH, Oct. 16-20th, 2011
Implementation Challenges for Sintered Silicon Carbide Fiber Bonded Ceramic Materials for High Temperature Applications
M. Singh Ohio Aerospace Institute
NASA Glenn Research Center Cleveland, OH 44135 (USA)
Abstract
During the last decades, a number of fiber reinforced ceramic composites have been developed and tested for various aerospace and ground based applications. However, a number of challenges still remain slowing the wide scale implementation of these materials. In addition to continuous fiber reinforced composites, other innovative materials have been developed including the fibrous monoliths and sintered fiber bonded ceramics. The sintered silicon carbide fiber bonded ceramics have been fabricated by the hot pressing and sintering of silicon carbide fibers. However, in this system reliable property database as well as various issues related to thermomechanical performance, integration, and fabrication of large and complex shape components has yet to be addressed. In this presentation, thermomechanical properties of sintered silicon carbide fiber bonded ceramics (as fabricated and joined) will be presented. In addition, critical need for manufacturing and integration technologies in successful implementation of these materials will be discussed.
https://ntrs.nasa.gov/search.jsp?R=20150009974 2020-07-01T11:34:55+00:00Z
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Implementation Challenges for Sintered Silicon Carbide Fiber Bonded Ceramic Materials for
High Temperature Applications
M. SinghM. SinghOhio Ohio Aerospace Aerospace InstituteInstitute
NASA Glenn Research CenterNASA Glenn Research CenterCl l d OH 44135Cl l d OH 44135
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Cleveland, OH 44135Cleveland, OH 44135
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Outline
• Introduction and Background
• Fiber Bonded Ceramics: Overview• Materials and Manufacturing
• Microstructure (SEM, TEM)
• Thermal Properties
• Key Implementation Challenges• Thermomechanical Performance
• Integration Technologies
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g g
• Robust Manufacturing and Cost
• Concluding Remarks
• Acknowledgments
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Ceramic Matrix Composites (CMCs): Past, Present and Future ?
• Tremendous potential for use of ceramic matrix composites in aerospace and ground-based applications.
• Many intrinsic advantages over other material classes.
• Unique capabilities relative to certain applications.
• Substantial, long-term government funding for research and development in these materials worldwide.
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• But many scientific, technical, economic, and cultural problems still remain in wide scale use of these materials.
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Timescale for Development and Applications of CMCs
Introduction/Background
Fiber Bonded Ceramics
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1960 1970 1980 1990 2000 2015Ceramic Fibers
MatricesInterphases
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Although more complex and more expensive than monolithic ceramics, the added “toughness” of CMCs make them more
inherently damage tolerant than monolithic ceramics.(Fiber Bonded Ceramics Could Play a Key Role)
Introduction/Background
Monolithic Ceramics -brittle, catastrophic failure
C it (CMC)
Suts
sile
Str
ess
sile
Str
ess Fiber Bonded Ceramics -
tough, “graceful” failure
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Composite (CMC) -tough, “graceful” failure
Longitudinal StrainLongitudinal Strain
PL=oTen
sT
ens
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SiC Fiber Bonded Ceramics
Processing and Microstructure
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Synthesis of Amorphous Si-Al-C-O Fiber
Polyalumino-Polyalumino-carbosilane
Melt spinning
@220°C
Curing
in Air @160°C
Firingin Ar gas
up to 1300°C
phou
sC
-O f
iber
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Formingcontinuouslyto fiber shape
Changing toceramic fiber A
mor
pSi
-Al-
C
T. Ishikawa, Ube Industries
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Fabrication of SiC Fiber Bonded Ceramics (SA-Tyrannohex)
AmorphousSi-Al-C-O fiber
Cut & Lamination
SA-Tyrannohex™
Fabric(8-harness satin)
Hot Pressing
Si1C1.5O0.4Al0.014Si C O Al
53 33 13.3 0.7
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at ~1900 ,50MPa,1h in Ar gas
Ube Industries
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Forming Process of SA-Tyrannohex during Hot Pressing
11 22 33
44 55
Under high pressure & high temp.in a hot press
Deforming fibers & Evaporating SiO and CO gas
Closed-pack hexagonal columnarstructure
C layer
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Carbon diffusion from the center of fibers to its surface
Unique SA-Tyrannohex structure
5µmSiC fiber
C layer
T. Ishikawa, Ube Industries
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Unique MicrostructureHexagonal columnar SiC
polycrystalline fibers
Microstructure of Fiber Bonded Ceramics
C layerpolycrystalline fibers 10-20 nm turbostratic carbon
interfacial layers
Good PropertiesHigh density (~98-99%)High thermal conductivity
(33 W/mK @ 1600°C)
5µmSiC fiber
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( @ )High strength sustained up to
1600°CFlexural strength~300 MPa
High fracture toughness (1200 J/m2 @ RT)
SiCSiC
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SiC Fiber Bonded Ceramics
Thermomechanical Properties
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Thermomechanical Evaluation of Flexural Stress Rupture Behavior (time-to-failure)
3mm × 4mm × 50 mm
Applied stress
SA-THX
20
Pre-heat treatment @1400°Cfor 10h in air
1µm outer silica coating
Time
Tem
pera
ture Desired test temp.
30minto equilibratethe temperature
pp
FracturedFractured
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Fractography of tested specimens in SEM
Focused on the tensile side40mm
20mm
50mm
3mm α-SiC
SA-THX
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Stress versus Lifetime Behavior for SA-Tyrannohex™ Tested up to 1150 C in air
400
500
ApparentThreshold
300
200
pp
lied
str
ess,
MP
a
700°C950°C
500°C
ThresholdStress: 200-225 MPa
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10-2 10-1 100 101 102 103 10410-3
Time to failure, h
1009080
Ap
70
950 C1150°C No distinguishable
difference existed in the stress-dependence
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Stress versus Lifetime Behavior for SA-Tyrannohex™ Tested up to 1400°C in Air
400
500
Apparent
300
200
pp
lied
str
ess,
MP
a
700°C950°C
500°C
ThresholdStress: 175 MPa
The time-to-failure ≥
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10-2 10-1 100 101 102 103 10410-3
Time to failure, h
1009080
Ap
70
950 C1150°C
1400°C1300°C
The time to failure ≥ 1300°C exhibited a stress-dependence
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Stress versus Lifetime Behavior of MI SiC/SiCand SA-Tyrannohex up to 1300°C in Air
in air400
500
700°CSintered SiCHi-Nic-MISiC
300
200
pp
lied
str
ess,
MP
a
700°C
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700 C950°C1150°C1300°C
10-2 10-1 100 101 102 103 10410-3
Time to failure, h
1009080
Ap
70
700 C950°C1150°C1300°C
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Fractography of SA-Tyrannohex after the Rupture Tests between 700-1400°C
250MPa @700˚C 265MPa @1150˚C
250MPa @1300˚C 250MPa @1400˚C
500nm 500nm
2µm 2µm
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2µm 2µm
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SiC Fiber Bonded Ceramics
Joining and Integration Technologies
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Critical Needs for Integration Technologies
• A wide majority of CMC components have to be integrated with existing metallic constituents or components either during component manufacturing or co po e ts e t e du g co po e t a u actu g oin service.
• It is important to understand the technical issues among the different material systems
• Robust integration technologies can also play a key role in manufacturing of large size components (beyond existing manufacturing capabilities) utilizing building
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existing manufacturing capabilities) utilizing building block approach.
• Building Block approach has been used through the ages and currently quite effectively in metal, polymer, and electronic industry.
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• Materials– SA-Tyrannohex with two
orientations• Parallel type• Perpendicular type
• Procedure
Active Metal Brazing of Fiber Bonded Ceramics
Cusil-ABATi il– AgCuTi brazing alloy
• Cusil-ABA• Ticusil
• Conditions– Temperature: 10-15°C above
liquidus– Hold time: 5 min– Vacuum level: 10-6Torr
Assembly
Load: 0.3-0.4N
VacuumSA-THX
Ticusil
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• Characterization– Mounted in epoxy, and
polished– Optical microscopy– SEM-EDS
NameComposition(wt%)
TL
(K)TS
(K)
CTE (×10-6K-
1)
Cusil-ABA
63.0Ag-35.25Cu-1.75Ti
1088 1053 18.5
Ticusil68.8Ag-26.7Cu-4.5Ti
1173 1053 18.5
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Brazing of SA-Tyrannohex Material to Itself using the AgCuTi Brazing Alloy
SA-Tyrannohex
AgCuTi alloy
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50µm
Uniform joint microstructure and good bonding
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Joining of SA-Tyrannohex Material to Itself using the AgCuTi Brazing Alloy (Cusil-ABA & Ticusil)
SA-THX
Cusil-ABA SA-THX
Ticusil Despite orientation of fiber and Ti content, microstructures of the joints were very similar
pe
4.5%Ti (Ticusil)1.75%Ti (Cusil-ABA)
5µm
SA-THX
Cusil-ABA
5µm
SA-THX
Ticusil
ar t
ype
Par
alle
l typ
SA-THXTicusil
Rea
cted
Rea
cted
inte
rlaye
rin
terla
yer
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5µm 5µmPer
pen
dic
ula Magnified
2µm
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• Interlayer of SA-THX/Ticusil • EDS mapping result
Microstructure of the Joint Interfaces
SA-THX
iCla
yer
mp
ou
nd CCPhase diagramPhase diagram
1
23 5
4
2µmAg (Cu)
Cu (Ag)
T
Ti-S
i co
m
atomic %
SiSi TiTi
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Pos. Al Si Ti Cu Ag
1 23 4 5
0000
1.1
00
39.08.0
98.5
00
50.187.9
0
16.098.510.94.10
84.01.5000
CuCu AgAg
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• Schematic • Effect of Ti on the thickness of TiC layer on SA-Tyrannohex
Summary of Joint Microstructure of SA-THXMaterials using AgCuTi Alloy Brazes
SA-THXAg (Cu)
1.2
m
• In the interface between SA-T h d th t l thi TiC
Cu (Ag)
TiC layerGranular
Ti-Sicompound
0
0.2
0.4
0.6
0.8
1
1.2
0 2 4 6
TiC
laye
r th
ickn
ess,
µm
Ti content %
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Tyrannohex and the metals, thin TiClayer and granular Ti-Si compound (could be Ti5Si3) were formed regardless of the orientation and Ti content.
• The joint microstructure of the SA-Tyrannohex using Ag-Cu-Ti alloy brazes was very similar regardless of the orientation and Ti content.
Ti content, %
Ti content Orientation Ti-Si region (µm)
1.75 wt%Parallel 0.82 ± 0.20Perpendicular 1.60 ± 0.68
4.5 wt%Parallel 2.16 ± 0.88Perpendicular 1.42 ± 0.45
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• Joint Materials– SA-THX( & ǁ)/Cusil-ABA
• Testing Machine– Capacity: 22.5 kN– Crosshead speed:
0 5mm/min
Procedure for Mechanical Evaluation
• Single lap offset shear test– Modified ASTM D905– R.T., 250, 650 and 750°C
• Melting point: 815°C
0.5mm/min– Atmosphere: air
Joint
Pushing rod
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Heater
StageFixture
Thermocouples
sample
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Mechanical Behavior SA-THX Joints as a Function of Test Temperature
Failed withinFailed withinSASA--THX ≤250THX ≤250°°CC
10
15
20
25
Lo
ad a
t fa
ilure
, kN
Perpendiculartype
Parallel-type
Failed in jointsFailed in joints≥650≥650°°CC
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0
5
0 200 400 600 800 1000
L
Temperature, °C
yp
Failed withinFailed withinSASA--THX ≤750THX ≤750°°CC
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Shear Strength of the Perpendicular-Type SA-THX Joints as a function of Test Temperature
The perpendicular type SA-THX joints tested above 650°C fractured100
120
Pa
Perpendicular-type
Failed withinFailed withinSATHX ≤250SATHX ≤250°°CC
Failed in JointsFailed in Joints
5
10
15
20
Load
at f
ailu
re, k
N
Perpendiculartype
Parallel-type
joints tested above 650 C fractured at the metal. The others joints while failed within the SA-THX materials.
In terms of these samples, shear strength can be obtained via this formula;
F20
40
60
80
She
ar s
tren
gth
of jo
int,
MP
The shear strength decreased with increase in temperatures
Failed in JointsFailed in Joints≥650≥650°°CC
Fractographiccharacterization
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00 200 400 600 800 1000
Temperature, °C
F
A00 200 400 600 800
Temperature, °C
with increase in temperatures
Failed withinFailed withinSATHX ≤750SATHX ≤750°°CC
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Summary of Fractography• Failure occurred between the filler
metal and TiO2 interaction layer
– TiO2 layer may be caused by oxidation of TiC, which was formed
SA
-TH
X
SA
-TH
X
TiC
Ag-
Cu
Ag
& C
u2
O
Cu
O
TiO 2
Cra
ckin
g pa
th
Ti-S
i
Ti-S
i-O
ack
s
by the reaction between Ti in the filler metal and C in SA-Tyrannohexduring the brazing.
• There are micro-cracks in SA-Tyrannohex in the vicinity of the interaction phase.
– The micro-cracks could be brought about by degradation of SA-
SA
-TH
X
SA
-TH
X
TiC
Ag-
Cu
TiC
Cra
ckin
g p
ath
Ti-S
i
Ti-S
i
cks
Mic
ro-c
ra
Obtained representative microstructure
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Tyrannohex strength, which would be caused by C migration in SA-Tyrannohex to form TiC.
• Since Cu reacts with O2, CuO and Cu2O phases were formed during the cooling after the test at 750˚C.
Mic
ro-c
rac
Predicted microstructure as the joint failure occurred at high temperatures
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Joining with Eutectic Phase Tapes (1 layer and 2 layers)
• SA-Tyrannohex (parallel) and SA-Tyrannohex (perpendicular)
• Joined with 2 mm offset for mechanical tests.
• Testing at R.T., 700ºC and 1200ºC
Ceramic Joining and Integration- Joining with Si-Hf Eutectic Phase Tape
Spot C Si Al Hf
1 63.12 36.88
2 64.30 35.70
3 67.75 32.25
4 63.82 35.40 0.78
5 55.93 44.07
6 56.83 43.17
7 55.28 44.72
8 32.89 67.11
40
60
80
100
120
140
ent Shear Strength, Mpa
8a 100.00
9 32.92 67.08
9a 100.00
10 32.34 67.66
10a 100.00
Spot C Si Hf
1 61.71 38.29
2 61 81 38 19
SEM and EDS of joints for parallel and perpendicular
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0
20
40
Appare
‖SA‐Tyrannohex 1 layer
‖SA‐Tyrannohex 2 layers
┴ SA‐Tyrannohex 1 layer
┴ SA‐Tyrannohex 2 layers
Apparent Shear Strength at Room Temperature
2 61.81 38.19
3 57.41 42.59
4 57.63 42.37
5 53.25 46.75
6 65.12 34.88
7 100.00
7a 31.28 68.72
8 100.00
8a 32.32 67.68
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SiC Fiber Bonded Ceramics
Long Term Challenges
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Environmental Issues in Manufacturing and Product Life Cycle Management
• ISO 14000 Standard for Environmental Management.
ISO 14001 d ISO 14004 d l ith E i t l• ISO 14001 and ISO 14004 deal with Environmental Management System (EMS)- 1996.
• EMS provides a framework for an organization to manage the impact of its activities on the environment.
• Provides tools to help companies realize their own environmental policies, objectives, and targets.
• In Europe, European Community (EC) has established an
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p , p y ( )Eco Management and Audit Scheme (EMAS) in 1997.
In Global Economy, Consumer Demand of High Quality Products with In Global Economy, Consumer Demand of High Quality Products with Low or No Environmental Impact, Standards Will Play Major RoleLow or No Environmental Impact, Standards Will Play Major Role
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Performance vs Cost Issue
• It is quite clear that CMC industry is in a real dilemma
CMC ( t ) d d f t t b t- CMC users (customers) demand performance at cost, but cost is typically driven by market volume.
- Small market volume means high cost and small number (or no) customers.
• Users (customers) are willing to pay the COST if the CMC is truly enabling.
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Concluding Remarks
• Fiber Bonded Ceramics have a lot of potential for niche high temperature applications but the manufacturing processes are still evolutionary. Their use has been limited due to limited manufacturing base and costdue to limited manufacturing base and cost.
• For the wide scale applications of these materials, reliable processes and properties have to be demonstrated at various levels (coupons to full scale components). In addition, multiscale modeling tools have to be developed and effectively utilized.
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• The CMC community has to leverage their resources and make a concerted effort in finding out multiple applications and educating customers. High market volume will drop the cost and will be able to sustain the supplier base.
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Acknowledgments
• Drs. T. Ishikawa and T. Matsunaga, Ube Industries, Inc., Japan
• Mr. Michael Halbig, NASA Glenn Research Center
• Mr. Craig E. Smith, Ohio Aerospace Institute
• Mr. Ray Babuder, Case Western reserve University
• Mr. Ronald E. Phillips, ASRC Corp., Cleveland, OH
• Dr. H-T. Lin, Oak Ridge National Laboratory, TN
• Prof. Julian Martinez-Fernandez, University of Seville, S i
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Spain
• Prof. Rajiv Asthana, University of Wisconsin-Stout, WI