NASA Technical Reports Server (NTRS) 20040112001: Optical Diagnostics for Thermal Barrier Coatings

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by  NASA Technical Reports Server (NTRS)

OPTICAL, MAGNOSTIES HOR THMGEMAT. BARRIER
COATINGS, 11 Eniedget, CM. Spucler and al Bens,
ASA Gana Reseach Covl, Cevolnd, OF RE, Martin,
Clevelind State Usiversiy, Clever, OL

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provide euperaure suing: wow J dhemogreit pbospber
Taper esi honcat tha TRC,
Optical Diagnostics
for
Thermal Barrier Coatings

J:L Eldridge, CM. Spuckler, and TJ. Bencle
NASA Glenn Research Center
Cleveland, OH

RE. Martin
Cleveland State University
Cleveland, OH

28th Annual Cocoa Beach Conference
vanuary 28, 2004

Background

+ Pracical end raliable dlagnostic tools ara roquited tor TBC heath
‘ontoring anda enable confident measurement of TEC
perlornance.

= leo TAC tw estes epplisaion ot TBS
ser edly nage TC epee
“Void trast at ia prelate oper
= Accurate maasurement of TSC perornaneypstentalto development)
aire nse oatngs, .
+ Mesaurements must dapth-panatating & nendetucive
= Damege Fronagaion hued below our,
+ TBC transluceney allows “windoy for optical techniques ta provide
capt penetialing, nondestucive dannastles.

a
Established Optical Techniques

= Infrared (IR) pyrometry provides depth-averaged TEC
temperaiure measurements.

"Lang wavologths (20 en} oan proves ce srk
= Cannot pobe thermal gradients,

+ Piezospectroscopy (Cr luminescence) has been
demonstrated to manitor strass state in thermally grown
oxide (TGO) beneath TBC. (U, Calfornia—Sania
Barbata, U. Connecticut)

very life 0 obtain -inssconce sgn haus hh
aiehintng damecprayed tees.

~ Noaswed T60 siese relaxation goours intial reoeding
Gcsrnnacie wh THe aie: eos dees net prov
Sor warns.

«IR thermography reveals damage-induced “hol spots” &

lateral ihetrnal prafies,

na dash sens ty or prebing thorma. graders,

Signiftcant camage req redo procuce “hotspots

= Mensur varsin rxpona net rats fe engine
ong.

Two Recent Approaches

+ Mike} rflsctenos
"Take advantage of mma THC ransparercy a MIP wavelengths
‘Porfor outed dare pr-seion& eon
Way be senso fo way egos of 730 fare.
‘Stony state fleas ages npr to olerer fr sagnslotng
thn msi aged ermogrephy
~ Obosurey sures cortamnation (nisleeing raul) |
peu fo high tmperate measurement
= Depth ponatatng. not deph-ecobes
+ Lam nescence-ssnsing for TCs ineerporlirg thormogranhic
paeaphors
Sra egi lace of amines ayars roi
‘Mlomatanan BC tenpurat'egradets& ines
+ liner I anemia al vsle vasearghis esl hy etry
Tigh santaa™-produciy meracton (umines=crot
{+ nero igh lerrsure meee tement:
Onecare by surace2entaminato seo 5p. no milading
ls.
rormegrak phosphor inearsation may degrade TAC peionmance
MIR Reflectance Operates at Wavelengths Where TBC
Exhibits Maximum Transmittance
———>

Freestanding
172um
plasms:
preyed aYS2

on

a 2 4 6 8 10
Wavelength (um)

Effect of Furnace Cycling on Hemispherical Reflectance

1 eyete = 45 min 1460°C + 15mm cooling to 120°C init
180 pm hick PS-EYSZMIGrALY bond coatene NS eubetrate

Th

Retlactance (8)

mining
Wavelength (um)
Effect of Furnace Cycling on Hemispherical Reflectance

180 um tek P8-2YS2MICrAIY bond eosUene NS substrate

Wavelength um)

Pas eycae
| soap
[209 cyt

4.0 um Reilectanee as Indicator for Remaining

TBC Life
” Pome,
gos
g a
£ forsee | | reflzctsnos ean
se Fee | |etare
2 came
oc "" 7
7

100 200
# of furnace cycles,

300
Delamination crack network formed after 180 cycles (2/4 TBC life)
Gradual progress on allows effective health monitoring

Predicted Effect of Crack on Hemispharical Reflectance
(based on zero-absorption four-flux model)

Reflectance (%)
eeugergasa®

te mw mew ae jis introduces

igh internal
‘TBC Optical Thickness, mgninten!

‘TaCierack Intertaco]
Filtering at 4 um Avoids OH and CO; Interference

96. ae
ao mg
ES 2%
Besd[ teat on

MIR Reflectance Imaging Approach

Imaging aparoach 9 more practi heath mentoring tol

Using vsua’nepection Pat provioos the patel resolution :0
joni a/oas 0! buried demaye or crosion

Sonus all ob acts are MIR erlons cilectance images are

biained hy sublracrg image obs! wih no Hluminatin ftom

image sbtained wt Mumination.

ao

‘am

2 mn
Reflectance Increases with Furnace Cycling

"180m tick PS-AYSZICEAIY bond coatene NS aubstate
‘Spoetal Reflectance

toe ight

aR rflsctance image
110 o we
cycles cycles

168 35 »
nycles — oyoles :

MIR Reflectance Intensity — 3D

Reflectance Increases with Furnace Cycling
MIR Reflectance Imaging
Effect of NiAl Backing — Simulates Substrate Presence

ate light im

eck

istanes (mm)

MIR Reflectance Imaging
Half-Backed PS-8YSZ TBC
Effect of 1100°C Heat Treatment on Hemispherical
Reflectance of EB-PVD TBC

“Ta apecimens & SEM courtesy of Uwe Shute, DLR

zy oe pressed

i

ee 200 hr 100%
spies aa

Wavelength

Effect of TBC Thickness on Hemispherical Reflectance
‘Thickness dependence can be used to monitor erosion

Frosctanding plasmivsprayed SYSZ

ve
Ge nie
ge J nee
= Reflectance: rowkn
| Secewes
a] weree

>of 4 6 8
Wavelength (microns)