NASA Technical Reports Server (NTRS) 20170005222: Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

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by  NASA Technical Reports Server (NTRS)

National Aeronautics and Space Administration
Environmental Stability and Oxidation Behavior of HfO -Si and
2
YbGd(O) Based Environmental Barrier Coating Systems for
SiC/SiC Ceramic Matrix Composites
Dongming Zhu, Serene Farmer, Terry R. McCue, Bryan Harder, Janet B. Hurst
Materials and Structures Division
NASA John H. Glenn Research Center
Cleveland, Ohio 44135
41st International Conference and Expo on Advanced Ceramics and Composites (ICACC’17)
January 22-27, 2017
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National Aeronautics and Space Administration
NASA EBC and CMC System Development
− Emphasize temperature capability, performance and long-term durability
• Highly loaded EBC-CMCs - Prime-reliant coatings
• 2700-3000°F (1482-1650°C) turbine and CMC combustor coatings
• 2700°F (1482°C) EBC bond coat technology for supporting next generation
– Recession: <5 mg/cm2 per 1000 h
– Coating and component strength requirements: 15-30 ksi, or 100- 207 MPa
– Resistance to Calcium Magnesium Alumino-Silicate (CMAS), impact and erosion
Step increase in the material’s temperature capability
TTeemmppeerraattuurree
3000°F SiC/SiC CMC airfoil
CCaappaabbiilliittyy
((TT//EEBBCC)) ssuurrffaaccee
and combustor
3000°F+ (1650°C+)
2800ºF
technologies
combustor
2700°F SiC/SiC thin turbine
2700°F (1482C)
TBC
EBC systems for CMC
IInnccrreeaassee iinn TT
airfoils
aaccrroossss TT//EEBBCC
2500ºF
2700°F (1482°C) Gen III SiC/SiC CMCs
Turbine TBC
CCeerraammiicc MMaattrriixx CCoommppoossiittee
2400°F (1316°C) Gen I and Gen II SiC/SiC
CMCs
SSiinnggllee CCrryyssttaall SSuuppeerraallllooyy
2000°F (1093°C), PtAl and NiAl bond coats
GGeenn.. IIVV
GGeenn IIIIII
GGeenn IIII –– CCuurrrreenntt ccoommmmeerrcciiaall
GGeenn II YYeeaarr
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National Aeronautics and Space Administration
Outline
• Advanced 2700°F capable EBC and bond coat developments
- Rare Earth – Silicon, i.e., YbGd-Si (O) and YbGd-Lu-Si (O) and Hafnia-Si
(HfO -Si) systems
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- Early systems cyclic oxidation results and Si composition optimizations
- Focus on oxidation kinetics studies of selected EB-PVD coatings using TGA
- Oxidation mechanisms and degradation mechanisms
• EBC - CMC system thermomechanical - environment testing, particularly
using laser rigs
- A Key step and capability for developments, and help composition optimization
and
• Summary
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National Aeronautics and Space Administration
NASA Advanced 2700°F Silicide Based Bond Coats – and
EBC Systems Processing for Various Component Applications
– Advanced coating systems developed for various processing to improve
Technology Readiness Levels (TRL)
– Composition ranges studied mostly from 50 – 80 atomic% silicon
• PVD-CVD processing, for composition downselects - also helping potentially develop a low cost CVD
or laser CVD approach
• Compositions initially downselected for selected EB-PVD and APS coating composition processing
PVD-CVD EB-PVD APS* FurnaceLaser/C
YSi YbGdYSi GdYSi HfO -Si 1; HfO2-Si VD/PVD
2
ZrSi+Y YbGdYSi GdYSi REHfSi YSi+RESilicate
REHfSi
ZrSi+Y YbGdYSi GdYSi GdYSi YSi+Hf-RESilicate
ZrSi+Ta YbGdYSi GdYSi GdYbSi2
ZrSi+Ta YbGdSi GdYSi-X GdYb-LuSi Used in ERA
NdYSi
HfSi + Si YbGdSi GdYSi-X Hf-RESilicate components as
part of bond coat
HfSi + YSi YbGdSi 1,2 system
Subelment
HfSi+Ysi+Si YbGdSi
demos
YbSi YbGdSi
YbSi Process and Hf-RE-Al-Silicate Used in ERA
HfSi + YbSi
composition components as
transitions part of bond coat
GdYbSi(Hf)
system
YYbGdSi(Hf) YbYSi
YbHfSi
YbHfSi
YbHfSi
YbHfSi
YbHfSi
APS*: or plasma spray related
YbSi
processing methods
US Patent Application S/N: 13/923,450 (LEW 18949-1), US Provisional Patent Serial No.: 62/329,500 (LEW 18949-2), LEW 19435-1. www.nasa.gov
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National Aeronautics and Space Administration
Oxidation Kinetics and Furnace Cyclic Behavior of RESi EBC
Bond Coats -
– Some early multi-component PVD processed systems showed excellent oxidation
resistance and furnace cyclic test (FCT) durability at 1500°C
– FCT and steam tests also performed for more advanced RESiO-Hf systems
5
4
m 4
c 0.0012
2/
g
m
n, 3 500 hr test, RREESSii((OO))
gai 0.0010 1500°C in O RESi(O)
ht 2 RESi(O)
g
ei 2 RESi(O)
w
ecific 1 YGdSi bond coat on SiC/SiC, 1500°C 4-sec 0.0008 RRREEESSSiii(((OOO)))
Sp Specific weight gain, mg2/cm4 m RESi(O)
c 0.0006 RESi(O)
/
0 2 RESi(O)
g
0 100 200 300 400 500 600
m RESi(O)
Time, hours HfO2-Si
p, 0.0004
HfO2-Si
K
Oxidation kinetics
RESiO 0.0002
2 2 7-x
RESi(O)
Transition region
SiC between Si-rich
and silicate regions
0.0000
An example of cross-section
60 65 70 75 80 85
TGA tested specimen
Silicon composition, at%
-
40 mm
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National Aeronautics and Space Administration
Oxidation Kinetics and Furnace Cyclic Behavior of RESi EBC
Bond Coats - Continued
– Some early multi-component PVD processed systems showed excellent oxidation
resistance and furnace cyclic test (FCT) durability at 1500°C
– FCT and steam tests also performed for more advanced RESiO-Hf systems
– FCT durability found to be closely related to temperature capability and oxidation
resistance of the coating systems
%
t
a

,
n
Di-silicides/disilicates o
i
t
a
r
t
n
e
c
n
Monosilicides/monosilicates o
c

n
o
c
RE2Si2O7-x il
i
RESi(O) S
Transition region
SiC between Si-rich
and silicate regions
An example of cross-section
TGA tested specimen
-
40 mm FCT life, Testing in Air at 1500°C, 1 hr cycles
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National Aeronautics and Space Administration
Oxidation Resistance of Plasma sprayed Based HfO -Si
2
─ TGA weight change measurements in flowing O
2
─ Parabolic oxidation kinetics generally observed
─ Solid-state reaction is also involved with the systems, and more complex behavior at 1400
and 1500°C
─ Improved oxidation resistance through APS plasma spray powder processing optimization
(AE10219 II; Sulzer/Oerlikon Metco) 60
AE 10219 Clad II 1200C
5.0 2cm 50 1300C
g/ 1400C
1500°C 1400°C 1300°C 1200°C n, m 40 1500C
ai
g
ht 30
4.0 eig
c w 20
cifi
4 pe 10
m 10219 Clad Ia S
3.0
c
/ Plasma spray processed 0
2g 0 2 4 6 8 10 12
m Activation energy 101 kJ/mol Time, hour1/2
p, 2.0 R2=0.98258
K
n 10218 Clad
l
1.0
Si
10219 Clad II
HfSiO
0.0
4
0.00055 0.0006 0.00065 0.0007 0.00075 0.0008
-1
1/T, K
- AE 10219: first Generation HfO -30wt%Si composite APS powders
2 HfO
2
- AE 10218 is HfO -30wt%Si composite APS powders used in NASA
2
ERA liner component demonstrations
Polished specimen microstructure after
- AE 10219 Clad II is second Generation HfO -30wt%Si composite
2
1400°C test (Hot pressed sample)
APS powders
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National Aeronautics and Space Administration
Microstructures of Furnace Cyclic Tested GdYbSi(O) EBC Systems
— Cyclic tested cross-sections of early PVD processed YbGdSi(O) bond coat
— Self-grown rare earth silicate EBCs and with some RE-containing SiO rich phase separations
2
— Relatively good coating adhesion and cyclic durability
1500°C, in air, 500, 1 hr cycles
- Complex coating architectures
after the testing
A - Designed with EBC like
compositions – Self-grown
EBCs
Composition (mol%) spectrum Area #1
B SiO2 67.98
Gd2O3 11.95
Yb2O3 20.07
Composition (mol%) spectrum Area #2
SiO2 66.03
Gd2O3 10.07
Yb2O3 23.9
B
A
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National Aeronautics and Space Administration
Microstructures of Cyclic Tested GdYbSi(O) EBC Systems-
Continued
— Cyclic tested cross-sections of early PVD processed YbGdSi(O) bond coat
— Self-grown rare earth silicate EBCs and with some RE-containing SiO rich phase separations
2
— Relatively good coating adhesion and cyclic durability
1500°C, in air, 500, 1 hr cycles
Outlined area Composition (mol%) Spot Composition (mol%)
SiO2 66.72 SiO2 96.15
Gd2O3 8.62 Gd2O3 1.2
Yb2O3 24.66 Yb2O3 2.64
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National Aeronautics and Space Administration
Experimental: NASA Yb,Gd,Y Rare Earth Silicate EBCs
— Yb,Gd(Nd),Y (or RE-Silicate) Multi-Component Rare Earth Silicate EBCs
— Sometime using fine alternating HfO and the silicates for top coats
2
— EB-PVD bond coat systems mostly focused on YbGdSi, YbGd-LuSi, and YbNdSi,
and HfO -Si
2
— Initial compositions optimized for the EBC bond coats: RE:Si 1:2; and Hf:Si 1:2 –
1:1
— Coating processed on SiC/SiC ceramic matrix composites for studies
— Processed using Directed Vapor EB-PVD at Directed Vapor Technologies
EBC
Bond Coat
SiC/SiC CMC
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