National Aeronautics and Space Administration
Advanced Woven SiC/SiC Composites for High Temperature Applications Gregory N. Morscher
Ohio Aerospace Institute/NASA Glenn Research Center Cleveland, OH
The temperature, stress, and environmental conditions of many gas turbine, hypersonic, and even nuclear applications make the use of woven SiC/SiC composites an attractive
enabling material system. The development in SiC/SiC composites over the past few years has resulted in significant advances in high temperature performance so that now
these materials are being pursued for several turbine airfoil and reusable
hypersonic applications. The keys to maximizing stress capability and maximizing temperature capability will be outlined for SiC/SiC. These include the type of SiC fiber,
the fiber-architecture, and the matrix processing approach which leads to a variety of matrix compositions and structure. It will also be shown that a range of mechanical,
thermal, and permeability properties can be attained and tailored depending on the needs of an application. Finally, some of the remaining challenges will be discussed in
order for the use of these composite systems to be fully realized. Composites at Lake Louise Canada
Advanced Woven SiC/SiC Composites for
High Temperature Applications
Gregory N. Morscher, Ohio Aerospace Institute
Special Acknowledgement:
Hee Man Yun, Matech/GSM
James A. DiCarlo and James D. Kiser, NASA Glenn Research Center Ram Bhatt, US Army
Composites at Lake Louise Canada October 28th to November 2nd, 2007
The Need for High Temperature
Load-Bearing
CMC
•
Current SOA is Sylramic-iBN
reinforced Melt (Si) -Infiltrated CMC
Æ
NASA N24A
– 1315oC use-temperature for ~ 1000
hours and 100 MPa – would like higher stress capability for turbine components
•
Higher temperature applications for
advanced turbine and scramjet
engines, TPS structures, leading edge
applications, and even nuclear
applications
prohibit the use of free
matrices with free Si
•
Therefore, need for
higher stress
capability
(e.g., blades) and
higher
temperature capability
CMC (e.g.,
leading edge and TPS structures)
V a n e 2 / L o t 1 V a n e 2 / L o t 1
Inlet Turbine Vane
Outline
• The best fiber: Sylramic-iBN for > 1300
oC
applications
– As the fiber goes, so goes the composite
• Fiber architectures that enable
– Understanding the effect of fiber architecture in
order to fabricate the best combination of
composite properties
• SiC matrices for higher temperatures
– Increasing temperature requirements prohibit free
Si
Fiber Comparison
1000 hr Use Temperature (σ
f= 500 MPa)
From, J.A. DiCarlo and H.M. Yun, Handbook of Ceramic Composites, Chapter 2 (Kluwer: NY, 2005)
Oxides
SiC-based
Best of small diameter = Syl-iBNSylramic-iBN:
Polycrystalline B-containing SiC fiber (Sylramic, processed by COIC) subjected to post-process nitrogen containing heat treatment at high temperature (> 1700oC). Removes B and improves creep-rupture propertiesSylramic-iBN Based Composites for Applications > 1300
oC
•
Sylramic-iBN = NASA derived heat treatments of Sylramic fiber
•
Excellent creep resistance and thermal stability (up to 1800
oC)
– Best mechanical performance at high temperatures
– In-situ grown (tailorable) BN-based interphase composition
– Enables high temp processing routes not possible with other fiber-types, usually at temperatures well above the application use temperature!
0.01 0.1 1 10 100 1,000 50 100 200 300 500 1,000 Rup ture Stren g th , M P a 10 20 50 100 R u p tu re St re n g th , k s i Stress-Rupture Time, hr SylramicTM SylramicTM – i BN Hi-Nic.S Tyranno SA (1,2) 0.01 0.1 1 10 100 1,000 50 100 200 300 500 1,000 Rup ture Stren g th , M P a 10 20 50 100 R u p tu re St re n g th , k s i Stress-Rupture Time, hr SylramicTM SylramicTM – i BN Hi-Nic.S Tyranno SA (1,2)
1400C
DiCarlo and Yun, 2005 0
0.2 0.4 0.6 0.8 1 1.2 1.4 1000 1200 1400 1600 Anneal Temperature, oC RT No rm a li z e d Re ta in e d S tr e n g th Syl-iBN CVI; 100 hr anneal HNS CVI; 100 hr anneal Syl-iBN MI; 500 hr anneal
Yun, DiCarlo, Bhatt & Hurst, Ceram. Eng. Sci. Proc., 2003
Fiber Architectures that Enable Processing and
Properties for Desired Components
Approach
Æ
Process a wide variety of fiber-architectures
in order to (1) determine the effect of architecture on
composite properties for the purpose of tailoring
properties in desired directions and (2) determine if these
architectures could be successfully fabricated in order to
anticipate processing further architecture modifications.
Sylramic Fiber (COI) Fabric Low Temp. CVI Si-BN Interphase Infiltration CVI SiC Matrix Infiltration MI SiC/SiC Weaving Reactor Reactor Silicon Melt Infiltration Furnace CVI Preform
Slurry Cast SiC Matrix SiC/SiC
preform
Standard Slurry Cast Melt-Infiltrated (MI) 2D&3D
Woven Composites (GEPSC, Newark Delaware)
For Syl-iBN,
special treatment prior to CVI Si-BN
Tailoring Cracking Behavior with Fiber Architecture
(Syl-BN MI Composites)
• A variety of architectures are being studied for the
Syl-iBN MI system to determine effect of fiber
architecture and fiber content on matrix cracking
– 2D five harness satin with different tow ends per inch
• Standard composite (N24A) = 8 layers of balanced 7.9 epcm (20 epi)
– 2D five harness satin with different tow sizes
– 3D orthogonal with different Z fibers – balanced and
unbalanced in X and Y direction
– Layer to layer angle interlock
– Through the thickness angle interlock (with low Y fiber
content)
≅
Unidirectional composite
– 2D five harness satin with high tow ends per inch in X
direction and rayon in Y direction
≅
Unidirectional
composite
Some
Cross-Sections
5HS UNI
AI UNI
3DO-R
3DO-Z
LTL AI
Braid
2D 5HS
N24A
Determination of Fiber Volume Fraction
fo = fraction of fibers that bridge a matrix crack (0 = loading direction), including fibers at an angle, e.g., a braided architecture
tw
R
N
N
N
A
A
N
f
ply f tow tows ply fc f f o 2 / /
π
=
=
t
R
epcm
N
N
f
o
ply
f
tow
f
10
2
/
π
=
Nf = total number of fibers in the cross-section of the tensile specimen,
Af = area of a fiber
Ac = cross-sectional area of the tensile specimen (tw) Nply = # of plys or layers through the thickness,
Nf/tow = # of fibers per tow (800
for Syl-iBN),
Ntows/ply = number of tows per
ply or layer
Rf is the fiber radius (5 mm or 0.005 mm for Syl-iBN).
epcm = tow ends per cm
w
epcm
N
tows ply10
322 205
0.18 2
Same as 3DO-Bal-Z except oriented in the X (fill) direction (7 layer) 3DO-Bal-Z-X [7] 317 248 0.17 2.05
Nearly balanced 3D orthogonal; Y (loading) direction = Sylramic single tow at 7.1 epcm,8 layer; X direction = Sylramic double tow at 3.9 epcm; Z fiber = ZMI
3DO-Bal-Z-Y [7] 336 238 0.20 1.95
Nearly balanced 3D orthogonal; Y (loading) direction = Sylramic single tow at 7.9 epcm,8 layer; X direction = Sylramic double tow at 3.9 epcm; Z fiber = Rayon
3DO-Bal-R-Y [7]
352 250
0.26 Triaxial braid; double tow; -67/0/67 – tested in hoop orientation so
fibers are oriented + 23oto testing axis, 4 layers
Braid [8]
480 197
0.19 2.1
Balanced 2D five-harness satin ply lay up; two tows woven together at 3.9 epcm, 8 plys. 2D 5HS [6] (double tow) See [6] 220 to 290 0.12 to 0.2 1.5 to 2.2 Standard balanced 2D five-harness satin; ply lay up; number of plys
varied from 4 to 8; epcm varied from 4.9 to 8.7. 2D 5HS [6]
204 125
0.10 0.96
Layer-to-layer angle interlock; 5.5 epcm, 3 layers LTLAI (1)
596 262 + 9
0.27 1.58
Unbalanced 3D orthogonal; Y (loading) direction = Sylramic at 9.8 epcm, 7 layers; X direction = Sylramic at 3.9 epcm; Z direction = ZMI 3DO-Un-Z (2) >575 275 + 9 0.28 1.53
Unbalanced 3D orthogonal; Y (loading) direction = Sylramic at 9.8 epcm, 7 layers; X direction = Sylramic at 3.9 epcm; Z direction = Rayon 3DO-Un-R (2) >472 305 + 4 0.23 2.0
Unbalanced through-the-thickness angle interlock; fill direction = Sylramic at 11 epcm, 7 layers; warp direction = low epcm ZMI and rayon AI UNI (2) >818 335 0.50 2.17
Unbalanced five-harness satin; fill direction = Sylramic at 17 epcm; warp direction = low epcm rayon
5HS UNI (1) UTS (MPa) E (GPa) Fiber fraction, fo, in load direction Thickness (mm) Description Composite
Modal Acoustic Emission of CMCs
0 50 100 150 200 250 Time, microseconds -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 A m p li tu d e , m V 0 50 100 150 200 250 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 A m p li tu d e m V (Channel 1) (Channel 2) ExtensionalFlexural(with some
superimposed extensional)
Reflections
Extensional
Reflections
Flexural(with some superimposed extensional)
Δtx 0 50 100 150 200 250 Time, microseconds -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 A m p li tu d e , m V 0 50 100 150 200 250 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 A m p li tu d e m V (Channel 1) (Channel 2) Extensional
Flexural(with some
superimposed extensional)
Reflections
Extensional
Reflections
Flexural(with some superimposed extensional)
Δtx AE AE AE AE Tabs Clip-on Extensometer x 25 mm a transducer AE AE AE AE Tabs Clip-on Extensometer x 25 mm a transducer
•Locate damage events and failure events Æ Δt
•Monitor stress(or time)-dependent matrix cracking Æ Cumulative AE Energy
•Identify damage sources, e.g. matrix cracks, fiber breaks Æ Frequency
RT 0
oσ/ε
of Different Architecture
Syl-iBN MI Composites
0 100 200 300 400 500 600 700 800 900 0 0.1 0.2 0.3 0.4 0.5 0.6 Strain, % Stress, MPa AI UNI, fo = 0.23 3DO Un-R fo = 0.28 5HS UNI fo = 0.5 3DO Un-Z fo = 0.27 Braid; fo = 0.26 5HS 7.9epcm fo = 0.19 (N24A) LTL AI fo = 0.1 3DO Bal-Z-Y;fo=0.17 5HS 4.7epcm fo = 0.12 3DO Bal-Z-X;fo=0.180
oAE of Different Architecture Syl-iBN MI
Composites
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 200 400 600 800 1000 Stress, MPa Norm Cum AE AI UNI, fo = 0.23 5HS UNI fo = 0.5 3DO Un-R fo = 0.28 3DO Un-Z fo = 0.27 5HS 7.9epcm fo = 0.19 (N24A) LTL AI fo = 0.1AE Onset (Matrix Cracking) Stress
3DO-Bal-Z-
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0 0.1 0.2 0.3 0.4 0.5 0.6 fo A E O n set S tr a in , % 2D 5HS 3DO Bal-Y braid 5HS - double tow N24A 3DO Unbalanced AI UNI 5HS UNI LTL AI 3DO Bal-X 0 50 100 150 200 250 300 350 400 450 500 0 0.1 0.2 0.3 0.4 0.5 0.6 fo A E O n s e t S tr e s s , M P a 2D 5HS 3DO Bal-Y braid 5HS - double tow N24A 3DO Unbalanced AI UNI 2D 5HS UNI w/Rayon LTLAI 3DO Bal-X
Calculating the unbridged
⊥
tow area
90 20 1 h epcm N A = hs− ⋅ ⊥ ( z) towY z Y tow t h w h w epcm w epcm A ⎥⎥⋅ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ + ⎪⎭ ⎪ ⎬ ⎫ ⎪⎩ ⎪ ⎨ ⎧ − + ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − ⋅ = − − ⊥ 2 / 1 2 2 10 10 z ply z ply h tw N h w epcm t epcm N A⊥= ⋅ = ⋅ 10 10 z tow h w epcm t epcm w epcm A ⋅ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎪⎭ ⎪ ⎬ ⎫ ⎪⎩ ⎪ ⎨ ⎧ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − + + ⋅ = − ⊥ 2 / 1 2 0 2 10 2 1 20 10 t w epcm A tow X x ⋅ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − = − ⊥ 10 ite Minicompos ite Minicompos h Length A⊥= ⊥ ⋅ ⊥y = 231.07x + 36.034 y = 242.14x + 89.015 0 50 100 150 200 250 300 0 0.2 0.4 0.6 0.8 1 fo / (tow height) 1/2 A E O n set S tr ess, M P a 2D 5HS 3DO Bal.-Y Braid 2D 5HS - double tow 2D 5HS N24A 3DO Unbalanced - Y LTL AI 3DO Bal - X through-the-width not through-the-width
Effect of f
oand max
⊥
tow size on Matrix Cracking Stress
y = 738.07x + 67.966 0 50 100 150 200 250 300 350 400 450 500 0 0.2 0.4 0.6 0.8 1 1.2 fo / (A⊥)1/2 A E O n set S tr ess, M P a 2D 5HS 3DO Balanced braid 5HS - double tow N24A 3DO Unbalanced AI UNI 1/3 tow area AI UNI 2D 5HS UNI w/Rayon LTL AI 3DO Bal-X y = 650x2/3 y = 738.07x + 67.966 0 50 100 150 200 250 300 350 0 0.1 0.2 0.3 0.4 0.5 y = 650x2/3
f
o/ (A
⊥)
1/2f
o/ (tow height)
1/21315
oC Creep-Rupture of Different Architecture Composites
•
Significant improvement (~ 100 MPa) in creep-rupture properties
for unbalanced fiber architectures with high fiber fraction in loading
direction over standard 2D five-harness composites
0 50 100 150 200 250 300 350 1 10 100 1000 Time, hr St re s s , M P a NASA N24A (fo=0.19) 3DO-Un-R (fo=0.28) 3DO-Un-Z (fo=0.27) AI-UNI (fo=0.23) failed well outside HZ ref. 15 ref. 14 ref. 16
Sylramic-iBN Reinforced SiC-based Matrix
Composites
Fabricate different matrix composites with the
same architecture:
8 ply, 7.9 epcm
Sylramic-iBN Composites: Processing Approaches
Woven Sylramic Preform
CVI Interphase
CVI SiC Partial Infiltration
SiC Slurry Infiltration
Si Melt Infiltration (MI)
Full CVI SiC CVI Si3N4 (thin)
PIP SiC or SiNC
Various fiber, interphase, and matrix treatments
to form iBN fiber and improve strength, creep,
cracking, and thermal properties
CVI SiC
CVI SiC
Composite
Composite
MI SiC
MI SiC
Composite
Composite
PIP
PIP
Composite
Composite
CVI PIP SiC
CVI PIP SiC
Composite
RT 0
oσ/ε
behavior of Syl-iBN Composites
0
50
100
150
200
250
300
350
400
450
500
0
0.1
0.2
0.3
0.4
0.5
0.6
Strain, %
Stress, MPa
Syl-iBN MI SiC f = 0.39; E=250 GPahysteresis loops removed
Syl-iBN PIP SiC f = 0.50; E=160 GPa
Syl-iBN CVI SiC
f = 0.39 E = 275 GPa
Syl-iBN CVI-PIP SiC f = 0.39; E=230 GPa (failed in radius)
FIBER
DOMINATED
MATRIX
DOMINATED
Ultimate Properties: Fiber Strength After Processing
Degradation in PIP Composites
For the best PIP:
σ
fibers~ 1600 MPa
0 50 100 150 200 250 300 350 400 450 500 0 0.1 0.2 0.3 0.4 0.5 0.6 Strain, % Stress, MPa Syl-iBN MI SiC f = 0.39; E=250 GPahysteresis loops removed
Syl-iBN PIP SiC f = 0.50; E=160 GPa
Syl-iBN CVI SiC f = 0.39 E = 275 GPa
Syl-iBN CVI-PIP SiC f = 0.39; E=230 GPa
(failed in radius)
For CVI-based:
σ
fibers~2350 MPa
Degradation in fibers
for PIP probably due
to inadequate
protection of fibers
Matrix Cracking (Acoustic Emission) of Syl-iBN
Composites
• For PIP (fiber dominated), very little AE activity and very little evidence of
stress-induced cracks – significant processing induced shrinkage cracks
• For MI, CVI, and CVI-PIP (matrix dominated), significant matrix cracking Æ
MI superior because pores are filled with silicon (removes stress
concentrators at tow intersections and induces residual compressive stress in matrix) 0 500 1000 1500 2000 2500 3000 0 100 200 300 400 500 Stress, MPa Cu mu lat ive AE En erg y MI SiC CVI SiC CVI-PIP SiC PIP SiC 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 100 200 300 400 500 Stress, MPa Norm Cum AE CVI-PIP SiC ~140 MPa CVI-SiC ~150 MPa MI-SiC ~180 MPa MI SiC CVI SiC
CVI-PIP SiC PIP SiC
PIP SiC has very little AE
activity
Design criteria for long term
use
Physical Properties of 2D-Woven Sylramic-iBN Panels
800 to 1600
(process
and filler)
2100 to
2400
(process)
~ 2400
~ 2400
Stress on
fibers at
failure, MPa
COIC
(Starfire
polymer)
GEPSC +
COIC
(Starfire
polymer)
GEPSC
Hyper-Therm
GEPSC
Goodrich
Composite
Vendors
Up to ~ 400
~ 400
~ 450
~ 450
UTS, MPa
~ 160
~ 210
~250
~ 250
E, GPa
~ 0.50
~0.38
~0.38
~0.38
f
~ 2.65
~2.70
~2.65
~2.75
Density,
g/cc
Syl-iBN PIP
Syl-iBN
CVI-PIP
Syl-iBN CVI
Syl-iBN MI
High Temperature 0
oCreep Rupture Behavior
-Si containing MI matrix composites begin to
degrade due to Si diffusion and attack of CVI SiC
and fibers above 1350
oC
-Therefore, tensile creep rupture tests were
performed between 1315
oC and 1450
oC in air to
Creep Rupture of Syl-iBN/SiC CMCs
1450
oC Creep
-At 1315C, all composites survive 103 MPa (15ksi) for hundreds of
hours
-At 1450C, CVI, PIP and CVI-PIP composites survive 69 MPa
(10ksi) for hundreds of hours
-PIP composites rupture at the highest composite stresses
because they have the highest volume fraction of fibers
1315
oC Creep
“Equivalent” is based on fo = 0.2
0
oCreep Rupture Dictated by Fiber Rupture
Properties at High Temperatures (1315
oC)
0 50 100 150 200 250 300 0 200 400 600 800 1000 Time, hr Rup
ture Stress, MPa
Syl-iBN MI Syl-iBN CVI Syl-iBN CVI-PIP Syl-iBN PIP PIP CVI SiC-Based 0 200 400 600 800 1000 0 200 400 600 800 1000 Time, hr S tress on fibers if fully loaded, MPa Syl-iBN MI Syl-iBN CVI Syl-iBN CVI-PIP Syl-iBN PIP 1315oC Creep Rupture
• Composite creep-rupture at 1315oC appears to be dependent on stress on
fibers for the three composite systems
• Starting strength of fibers in PIP matrix ranged from 1300 to 1600 MPa compared to ~2400 MPa for other systems. Æ Starting strength of fibers not a great factor for high temperature creep rupture
0
oCreep Rupture Dictated by Fiber Rupture
Properties at High Temperatures (1450
oC)
• Composite creep-rupture at 1450oC appears to be dependent on stress on fibers for
CVI and PIP composite systems; however, MI creep-rupture significantly lower
• Starting strength of fibers in PIP matrix ranged from 1300 to 1600 MPa compared to ~2400 MPa for other systems. Æ Starting strength of fibers not a great factor for high temperature creep rupture
0 20 40 60 80 100 120 0 100 200 300 400 500 600 S tr e ss, M P a 0 100 200 300 400 500 600 700 0 100 200 300 400 500 600 S tr e s s o n fib e rs if fu lly lo a d e d , M P a
1450
oC
1450
oC
MI CVI PIP MI CVI PIP0
oCreep Rupture of Composites are Comparable to
Fiber Rupture Properties at High Temperatures
•
Creep rupture life generally greater than comparable fiber-only
data, but follow same general trend
0 500 1000 1500 2000 2500 3000 0 10000 20000 30000 40000
Larson Miller Parameter, (T+273) [Log(t) +22]; T in oC, t in hr.
Stress on fibers, MPa
Syl-iBN MI Syl-iBN CVI Syl-iBN CVI-PIP Syl-iBN PIP Fiber Data Tow data 815C 1200C 1315C 1450C 0 500 1000 1500 2000 2500 3000 20000 25000 30000 35000 40000 45000
Larson Miller Parameter, (T+273) [Log(t) +22]; T in oC, t in hr.
Stress on fi be rs, MPa Syl-iBN MI Syl-iBN CVI Syl-iBN CVI-PIP Syl-iBN PIP Fiber Data 1200C 1315C 1450C
Out of Plane Properties for 2D-Woven Panels
1200
150
2000
25
Permeability,
mtorr/m**
4
10
5 {8}
--K33
(1400
oC),
W/mK
8
28
18 {28}
25
K33 (25
oC),
W/mK
23
10
7 {5}*
17
ILT strength,
MPa
Syl-iBN
PIP
Syl-iBN
CVI-PIP
Syl-iBN
CVI
Syl-iBN
MI
*{ } indicates after a special annealing treatment
Implications and Conclusions
• A plethora of properties (strength, thermal conductivity, permeability, etc…) can be tailored with the different SiC matrix processing routes available
– Further refinement and optimization can be made with architectures and heat treatments (not discussed in this presentation)
• High temperature creep rupture properties appear to be controlled by fiber creep rupture properties
– Starting strength of fibers not a factor at higher temperatures
– Nature of crack growth and fiber creep-rupture properties needs to be better understood to quantify life-degrading mechanism(s)
• High temperature (1400C+), highest stress capability is with PIP matrix composites because higher fiber volume fractions are attainable
– However, for high thermal conductivity, high off axis in-plane strength, and
low permeability applications, CVI or CVI-PIP will be required – Fiber
fraction in desired directions could be increased with modified architectures to enhance properties
– The ability to better protect the fibers during PIP processing may result in higher use-stress capability or at least retained strengths
• Sylramic-iBN fiber-types are necessary to achieve maximum properties
– Other fiber types degrade with advanced processing temperatures and/or lack creep resistance
– Newer advances to Sylramic-iBN types (“Super Sylramic”) of fibers should increase high temperature performance