ENVIRONMENTAL BARRIER COATINGS FOR TURBINE …
Transcript of ENVIRONMENTAL BARRIER COATINGS FOR TURBINE …
ENVIRONMENTAL BARRIER COATINGS FOR TURBINE ENGINES: A DESIGN AND PERFORMANCE PERSPECTIVE
Dongming Zhu, Dennis S. Fox, Louis Ghosn, James L. Smialek, and Robert A. Miller
NASA Glenn Research Center, USA
Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.
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Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective
Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective
Dongming Zhu, Dennis S. Fox, Louis Ghosn, James L. Smialek, Robert A. Miller
Durability and Protective Coatings BranchMaterials and Structures Division
NASA John H. Glenn Research Center
This work was supported by NASA Fundamental Aeronautics ProgramsThe 33rd International Conference on Advanced Ceramics & Composites
Cleveland, Ohio 44135, USA
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The 33rd International Conference on Advanced Ceramics & CompositesDaytona Beach, Florida
January 18-23, 2009
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Revolutionary Ceramic Coatings Greatly Impact Turbine Engine TechnologyEngine Technology
— Ceramic barrier coatings can significantly increase gas temperatures, reduce cooling requirements, improve engine fuel efficiency and reliability
Combustor Vane Blade Ceramic nozzlesCombustor Vane Blade Ceramic nozzles
>300°F increase
Turbineincrease
CMC combustor liner and vaneliner and vane
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(a) Current T/EBCs (b) Advanced T/EBCs
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Revolutionary Ceramic Coatings Greatly Impact Turbine Engine TechnologyEngine Technology
— Ceramic barrier coating system development goals- Meet next generation engine temperature, performance and durability requirements- Help fundamental scientific understanding, database and design tool development- Increase the coating Technology Readiness Levels (TRL)
Temperature Capability (T/EBC) surface
Temperature Capability (T/EBC) surface
3000°F+ (1650°C+)p y ( )
Increase in ∆T across T/EBC
p y ( )
Increase in ∆T across T/EBC Si N and coating systems
2700°F (1482°C)
2400°F (1316°C)
G IV
Single Crystal Superalloy
Ceramic Matrix Composite
G IV
Single Crystal Superalloy
Ceramic Matrix Composite
Si3N4 and coating systems
2000°F (1093°C)
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Gen I
Gen II – Current commercialGen III
Gen. IV
YearGen I
Gen II – Current commercialGen III
Gen. IV
Year
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Outline
─ High-heat-flux and simulated engine test approaches for ceramic coating development
─ The 2700°F thin turbine TEBC systems for SiC/SiC CMCs and Si3N4
─ Coating durability and stability evaluations
─ Summary and directions
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High-Heat-Flux Testing Approach– High-heat-flux tests crucial for the coating development
• Temperature gradient requirements: 400-600°F across 5-10 mil coatings
NASA CO Laser RigNASA CO2 Laser Rig
T
Heat flux cooling
Distance from surface
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Current capability up to 315 W/cm2 for TBCs
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High Pressure Burner Rig for Thermal and Environmental Barrier Coating DevelopmentBarrier Coating Development
─ Realistic engine combustion environments for specimen and component testing
High Pressure Burner rig (6 to 12 atm)C t d t bi t t fi t
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Coated turbine vane test fixtures
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High Pressure Burner Rig for Thermal and Environmental Barrier Coating DevelopmentBarrier Coating Development
• High Velocity and High Pressure Burner Rig Testing – High velocity testing for ceramic specimens– Optimum heat flux regime determined
200 1000Chamber pressureGas velocityp g
140
160
180
600
800Heat flux
Gas velocity
, W/c
m2
si; g
as v
eloc
ity, m
/s
80
100
120
200
400Hea
t flu
x
Cha
mbe
r pre
ssur
e; p
60
80
010 15 20 25 30 35 40
Pressure difference in combustor and test chamber, psi
Combustion flow
TC
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seen from viewport
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Multi-Functionally Graded Environmental Barrier Coatings for Si-based Ceramic Componentsfor Si based Ceramic Components
– Multifunctionally Graded Materials for SiC/SiC CMC and Si3N4 applications
Hi h t bilit id it l ith d d i t l i t l b i• High stability oxide composite layer with graded interlayer, environmental barrier and advanced bond coats
• Alternating composition layered coatings (ACLCs) and nano-composite coatings
Advanced EBCsbond coats
Interlayer: Compositional layer graded system -compositeLow expansion, high strain tolerance HfO2 & RE aluminosilicates
SiC/SiC CMC or Si3N4
HfO2 and HfO2 composites
Doped mullite/HfO2with ACLC (Hf rich bands)
Increased Si activity
Increased dopant RE/Transition metal concentrations & increased Al/Si ratio( )
Oxide and RE aluminiosilicate bond coats(High temperature capable with self-healing)
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Environmental Barrier Coatings Processed on Complex-Shaped SpecimensShaped Specimens
─ Thinner coating processing technologies developed for complex shaped components
Plasma-spray processing of Environmental barrier coatings for
various components
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Thin Turbine Blade CMC Coatings will be Pursued using Hybrid Plasma Vapor Deposition TechniqueHybrid Plasma Vapor Deposition Technique
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Sulzer plasma vapor deposition
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TEBCs Evaluated for Thermomechanical Fatigue (TMF) ResistanceResistance
-10 Hz, R ratio ~0, maximum mechanical load 250 MPa (36ksi) at 2200°F- Coating achieved excellent durability without failure after 250 hour testing- The system durability is currently limited by the CMC TMF capability and variabilityy y y y p y y
1.6 in
(a) Specimen testing (b) Specimen failure
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TEBCs Evaluated for ThermoMechanical Fatigue (TMF) Resistance - ContinuedResistance - Continued
300
coating
0
100
200
s, M
Pa
coating
-200
-100
Stre
s
-3000 0.5 1 1.5 2 2.5
Distance from surface, mm
Max 250 CMC MPa@2200°F, cyclic;
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CMC temperature modeling
@ , y ;Failed at 5x105 cycles
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Long-Term High Heat Flux Thermal Gradient Cyclic Testing of an Advanced TEBC Coating on SiC/SiC
Ceramic Matrix Composite- Coating successfully tested at Tsurface 2700°F and Tinterface 2400°F 250 hrs (1 hr hot hour cycles in air)
5.0
6.0
1600
y, W
/m-K
3 0
4.0
5.0
1200
Tsurfacecond
uctiv
ity
atur
e, °C
Tback=~1316°CTsurface=~1482°C
2.0
3.0
400
800
kcera
TsurfaceTinterfaceTback
zed
ther
mal
c
Tem
pera
Thin coating turbine CMC demonstrated high-heat-flux
0.0
1.0
0
400
0 50 100 150 200 250 300
Nor
mal
iz
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gcyclic durability at 2700˚F
0 50 100 150 200 250 300Time, hours
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High Pressure Burner Rig Durability Evaluations
- High Pressure Burner Rig Stability being evaluated for TEBCs on SiC/SiC- High stability coatings being down-selected
1AS800SN2822 -h
1300Temperature, °C
14001500 12001600
SiC/SiC under high velocity
0.1
SiC/SIC CMCLa
2Hf
2O
7
HfO2 (doped)
RE-Hf-luminosilicatesBSASan
ge, m
g/cm
2
0.01
c w
eigh
t cha Rare earth silicates
BSAS Baseline
0.0010 0005 0 00055 0 0006 0 00065 0 0007 0 00075 0 0008
Spec
ific
Future EBC stability development goal
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0.0005 0.00055 0.0006 0.00065 0.0007 0.00075 0.00081/T, K-1
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Summary• Advanced ceramic turbine component testing capabilities established
• Advanced thermal and environmental barrier coatings developed and• Advanced thermal and environmental barrier coatings developed and processed on complex-shaped components
• Coating stability demonstrated in high velocity-high pressure burner rigCoating stability demonstrated in high velocity high pressure burner rig simulated engine environments
• Coated CMC system low cycle fatigue durability demonstrated at 2700˚Fy y g y
• Coated CMC system TMF evaluated at 2200°F
• Heat transfer, fracture mechanics and stochastic approaches being established to develop coated CMC life prediction models
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AcknowledgementThe work was supported by NASA Fundamental Aeronautics
Program, Supersonics Project.
The authors are grateful to Bob Pastel for performing the high pressure burner rig tests.
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