Luminescence-Based Diagnostics of Thermal Barrier Coating Health and - - PowerPoint PPT Presentation

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Luminescence-Based Diagnostics of Thermal Barrier Coating Health and Performance

Jeffrey I. Eldridge NASA Glenn Research Center Cleveland, OH

National Aeronautics and Space Administration

37th International Conference on Advanced Ceramics & Composites Daytona Beach, FL January 29, 2013

https://ntrs.nasa.gov/search.jsp?R=20130011545 2018-07-09T20:05:26+00:00Z

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Acknowledgments

• NASA GRC

– Dongming Zhu (High heat flux testing) – Tim Bencic (2D surface temperature mapping) – Joy Buehler (Metallography)

• Penn State

– Doug Wolfe (EB-PVD)

• U. Connecticut

– Eric Jordan (SPPS)

• Metrolaser

– Tom Jenkins (VAATE engine test team)

• Emerging Measurements

– Steve Allison (VAATE engine test team)

• Funding by NASA Fundamental Aero and Air Force

Research Laboratory.

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Motivation

• Address need to test & monitor performance & health of TBCs.

– Lab environment assessment tool – Engine environment validation tool

• Essential for safely increasing engine operating temperatures.

Approach: Luminescence-Based Monitoring of TBC Performance

• Multifunctional TBCs with integrated diagnostic capabilities
• Erosion monitoring
• Delamination progression monitoring
• Temperature sensing

– Above & below TBC – Engine environment implementation – 2D temperature mapping

TBC Translucency Provides Window for Optical Diagnostics

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1 mm thick 13.5 YSZ single crystal (transparent) 135 µm thick Plasma-sprayed 8YSZ (translucent)

Backlit by overhead projector.

Light Transmission Through YSZ

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606 nm Eu3+ emission

Undoped YSZ YSZ:Eu YSZ:Tb PtAl bond coat Rene N5 superalloy substrate

UV illumination 543 nm Tb3+ emission

Erosion monitoring by luminescence detected from exposed YSZ:Eu and YSZ:Tb sublayers Coating Design

Erosion Detection Using Erosion-Indicating TBCs

Erosion Depth Indication Using Eu- and Tb-Doped YSZ

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coating surface, white light illumination coating surface, UV illumination erosion crater

Luminescence reveals location and depth of coating erosion.

1 cm 1 cm 165 µm sublayer-doped 7YSZ/PtAl/Rene N5

*EB-PVD TBCs produced at Penn State, D.E. Wolfe.

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562 nm Er3+ emission (high intensity) 562 nm Er3+ emission (low intensity) 980 nm illumination

Undoped YSZ Er + Yb-doped YSZ NiPtAl bond coat Rene N5 superalloy substrate delamination reflects excitation & emission

Detecting TBC Delamination by Reflectance-Enhanced Upconversion Luminescence

• Two-photon excitation of Er3+ produces upconversion luminescence at

562 nm with near-zero background for strong delamination contrast.

• Yb3+ absorbs 980 nm excitation and excites luminescence in Er3+ by

energy transfer.

• Delamination contrast achieved because of increased reflection of

excitation & emission at TBC/crack interface. upconversion

EB-PVD (Penn State)

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EB-PVD TBCs*

10 µm 50 µm

SEI BEI

YSZ

YSZ:Er(1%),Yb(3%)

NiPtAl

6 µm 130 µm

Rene N5 YSZ:Er,Yb Undoped YSZ

*EB-PVD TBCs produced at Penn State, D.E. Wolfe.

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Upconversion Luminescence Images During Interrupted Furnace Cycling for EB-PVD TBC with YSZ:Er(1%),Yb(3%) Base Layer

1cm

1 furnace cycle = 45min @1163°C + 15 min cooling

7.5 sec acquisition

1 cycle 10 cycles 20 cycles 30 cycles 40 cycles 0 cycles 60 cycles 80 cycles 100 cycles 120 cycles 140 cycles 160 cycles 180 cycles 200 cycles 220 cycles 240 cycles 260 cycles 280 cycles 300 cycles 320 cycles 340 cycles 360 cycles 380 cycles 400 cycles 420 cycles 440 cycles 460 cycles 480 cycles 500 cycles 520 cycles 540 cycles 560 cycles 580 cycles 600 cycles 620 cycles 740 cycles 640 cycles 660 cycles 680 cycles 700 cycles 720 cycles 745 cycles

YSZ

YSZ:Er(1%),Yb(3%)

NiPtAl

6 µm 130 µm

Rene N5

Batch 1

10

0.5 1 1.5 2 2.5 3 3.5 4 4.5 100 200 300 400 500 600 700

Furnace Cycles Luminescence Intensity Ratio

#1 fails at 620 cycles #2 fails at 500 cycles #3 fails at 745 cycles

Change in Upconversion Luminescence Intensity with Furnace Cycling to TBC Failure

early indication of TBC life

Failure Progression

EB-PVD TBC with YSZ:Er(1%),Yb(3%) Base Layer

400 cycles

Bright spots produced by large-separation micro- delaminations between TBC & TGO produced by bond coat instabilities (rumpling). Small microcracks between TBC & TGO increase intensity but may not be resolved individually TGO growth during furnace cycling

Microdelamination + TGO growth

• Delamination increases luminescence intensity.
• TGO growth decreases luminescence intensity.

Luminescence Image

10 µm

200 cycles

10 µm

700 cycles

10 µm

30 cycles

10 µm

0 cycles

10 µm

1cm

200 cycles

10 µm

Monitoring TBC Delamination Around Cooling Holes

TBC-coated specimen with 0.020” diam laser-drilled cooling holes at 20º.

• Problem: Cooling holes in turbine blades and vanes can act as

stress-concentrating failure initiation sites for surrounding TBC. Potential severity of these effects are unknown.

• Objective: Determine the severity of the effect of cooling holes
• n the lifetime of surrounding TBC using upconversion

luminescence imaging.

• Approach: Performed luminescence imaging during interrupted

furnace cycling of TBC-coated specimens with arrays of 0.020” diameter laser-drilled cooling holes.

20º hole pattern (typical angle for turbine blades) Top view Side view

20º

Monitoring Delamination Around Laser-Drilled Cooling Holes by Upconversion Luminescence Imaging During Furnace Cycling

7.5 sec acquisition

280 cycles 300 cycles 360 cycle 340 cycles

1 furnace cycle = 45min @1163°C + 15 min cooling

1 cm

YSZ

YSZ:Er(1%),Yb(3%)

NiPtAl

12 µm 130 µm

Rene N5

320 cycles 400 cycles 380 cycle 420 cycles White light image 460 cycles 480 cycles 500 cycles 520 cycles Upconversion luminescence image 440 cycles

Effect of Cooling Holes on TBC Life

• Luminescence imaging easily detects delamination

around cooling holes.

• Local delamination does initiate around cooling holes

but exhibits very limited, stable growth.

• The unstable delamination propagation that leads to

TBC failure actually AVOIDS vicinity of cooling holes.

• Significance: Cooling holes in turbine blades and

vanes do not shorten TBC life and their behavior as debond initiation sites can be tolerated safely.

Luminescence-Based Remote Temperature Monitoring Using Temperature-Indicating TBCs

Undoped YSZ Eu-doped YSZ PtAl bond coat Rene N5 superalloy substrate pulsed 532 nm illumination

Temperature (oC)

200 400 600 800 1000 1200

Asymptotic Decay Time (µsec)

0.1 1 10 100 1000 10000

606 nm Eu3+ emission (with temperature- dependent decay)

• 4
• 3
• 2
• 1

1 2 1 2 3 4 5

Time (µsec) ln [Emission Intensity (V)]

5 mil undoped YSZ/1 mil YSZ:Eu hitemp decay

• 6
• 5
• 4
• 3
• 2
• 1

1 2 3 4 5

Time (µsec)

500 C 550 C 600 C 620 C 640 C 660 C 680 C 700 C 720 C 740 C 760 C 780 C 800 C 820 C 840 C 860 C 880 C 900 C 920 C 940 C 960 C 980 C 1000 C

Buried Eu-doped YSZ layer, Eu3+ luminescence decay Surface Eu-doped YSZ layer, Eu3+ luminescence decay

Eu-doped YSZ

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50 µm undoped YSZ (118 µm) YSZ:Eu (36 µm)

Buried Eu-doped YSZ, Eu3+ luminescence image

PtAl

• r

Decay Time vs. Temperature Calibration

NASA GRC High-Heat-Flux Laser Facility

• Proof-of-concept with easy
• ptical access, no radiative

background, no probe heating issues. Williams International Combustor Burner Rig

• Address probe/TP survivability

& ability to “see” through flame. AEDC J85-GE-5

• Probe/translate through

afterburner flame.

• Opportunity to test

excitation/collection integrated probe. Demonstrated to 1360ºC. Demonstrated to >1400ºC.

AFRL Versatile Affordable Advanced Turbine Engines (VAATE) Project Gas Turbine Engine Sensor and Instrumentation Development

Demonstrated to >1300ºC. Goal: Demonstrate thermographic phosphor based temperature measurements to 1300ºC on TBC-coated HPT stator on Honeywell TECH7000 demonstrator engine. Honeywell TECH7000

1E-05 0.0001 0.001 0.01 200 400 600 800 1000

PMT Signal (V) Time (µs)

2.5 mm 6.9 mm 11.2 mm 15.7 mm 20 mm 24.4 mm 28.8 mm 33.1 mm

Distance from edge

Temperature Line Scan Across Hot Spot During Williams Combustor Burner Heating

Traversing High-Flame Hot-Spot Luminescence from YAG:Dy Coating

1 2 3 4 5 6 7 8 1 10 100 1000 200 400 600 800 1000 1200 1400 1600 1800

Decay Time (µs) Temperature (ºC)

range of confidence

High-Flame Temperature Line Scan

1 10 100 1000 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600

5 10 15 20 25 30 35

Decay Time (usec) Temperature C distance from edge (mm)

substrate melting! Luminescence emission

• bserved

through 456 nm bandpass filter

Implementation of Ultra-Bright High-Temperature Phosphor

• Breakthrough discovery* of exceptional high temperature

retention of ultra-bright luminescence by Cr-doped GdAlO3 with orthorhombic perovskite crystal structure: Cr-doped gadolinium aluminum perovskite (Cr:GAP).

– High crystal field in GAP suppresses thermal quenching of luminescence. – Novel utilization of broadband spin-allowed emission extends luminescence to shorter wavelengths where thermal radiation background is reduced.

• Enables luminescence-based temperature

measurements in highly radiant environments to 1250ºC.

– Huge advance over state-of-the-art ultra-bright luminescence upper limit of 600ºC.

*J.I. Eldridge & M.D. Chambers

Demonstrating Temperature Measurement Capability

Time-Averaged Luminescence Emission from Cr(0.2%):GAP Puck Temperature Dependence

550 600 650 700 750 800 850 Intensity (arb.units) Wavelength (nm)

20C 90C 284C 385C 484C 587C 686C 780C 880C 977C

bandpass

Coatings for 2D Temperature Mapping

Luminescence Decay Curves from 25 µm Thick EB-PVD Cr:GAP Coating

1E-05 0.0001 0.001 0.01 0.1 0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04

Intensity (V) Time (sec)

482°C 588°C 682°C 785°C 879°C 977°C 1076°C

Superb signal-to-noise from thin 25 µm thick coating confirms retention of ultra-bright luminescence at high temperatures.

2 1

/ 2 / 1

Fit to

τ τ t t

e I e I I

− −

+ =

Demonstrating Temperature Measurement Capability

Calibration of Decay Time vs. Temperature for GAP:Cr Coating

Temperature (ºC)

200 400 600 800 1000 1200

Decay Time (sec)

1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1

kT E Eq kT E kT E R E

e e e

/ ) ( / / 2 1

3 1 Fit to

∆ + ∆ − ∆ − ∆ −

+ + + = β α τ τ

Two distinct regions 200ºC<T<750ºC: less temperature sensitive T>750ºC: more temperature sensitive

2D Temperature Mapping of Effect of Air Cooling Jets

Laser heat flux

Air Jet Fixture for Laser Heat Flux Testing

4 cooling jets nozzle 970°C 980°C 990°C 1000°C 1010°C 1020°C 1030°C 1040°C 1050°C

Sequence of gated images (Tim Bencic, NASA GRC) 2D Temperature Map (B&W) 2D Temperature Map (color)

Temperature (ºC)

200 400 600 800 1000 1200

Decay Time (sec)

1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1

Temperature determined from decay time at each pixel. GAP:Cr Decay Time vs. Temperature Calibration

Insensitive to surface emissivity & reflected radiation!

1 cm 1 cm Courtesy of Dongming Zhu, NASA GRC

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Summary

• Luminescence-based sensing successfully monitors

TBC health & performance.

– Erosion indication by self-indicating TBCs – Delamination progression monitoring by upconversion luminescence imaging

• Predictive for remaining TBC life
• Cooling hole debond initiation sites safely tolerated.

– Temperature sensing by luminescence decay time behavior

• Surface & depth-penetrating measurements
• Ultra-bright high-temperature GAP:Cr phosphor enables 2D

temperature mapping.

• Nearing engine-test-ready status.