Groupe Français de Spectroscopie Vibrationnelle, 25, 26 et 27 JANVIER 2006,Spectroscopies Infrarouge et Raman« Mesures in situ et rayonnement thermique »
THERMAL BARRIER COATINGSTHERMOMETRY BY FLUORESCENCE
THERMAL BARRIER COATINGSTHERMOMETRY BY FLUORESCENCE
Molly Gentleman, Matt Chambers, Samuel Margueron and David R. Clarke
Materials Department, College of EngineeringUniversity of California, Santa Barbara,
CA 93106-5050
PlanPlan
Thermal Barrier Coatings
Fluorescence Thermometry of Eu:YSZ
Current issues in calibrations:– Effect of high energy excitation– Effect of reabsorption and energy transfer
Thermal Barrier CoatingsThermal Barrier Coatings
Moteur M88(Snecma)
150 µm
(ONERA)
Gradient 1 MK/m!
Materials EngineeringMaterials Engineering
YSZ: t’-(ZrO2 -7wt% Y2O3)Low conductivity, higher toughness Porous, columnar (EB-PVD)Optically Transparent (VIS-NIR)
Extract from: CONCEPTS FOR LUMINESCENCE SENSING OF THERMAL BARRIER COATINGS, M. Gentleman and D. R. Clarke,HYPERCOAT NSF-EU PROGRAM
Effects of radiative transfer, sintering, pollution, erosion
Fluorescence (Phosphorescence) Thermometry
Fluorescence (Phosphorescence) Thermometry
Interests : Remote sensing (In-Situ) « Independent » of optical path and gas emission Based on selective lifetime measurements
General issues :Intensity at high temperature (thermal quenching) Remote collection systemCMAS (pollutions infiltration)Others effect and noise (thermoluminescence, defects luminescence, impurities…)Doppler effect for measurements on mobile parts
Feist J. P, Heyes A. L (2000) “Europium-doped Yttria-stabilized Zirconiafor High-temperature Phosphor Thermometry”, Proceedings of the I MECH EPart L Journal of Materials: Design and Applications, Volume 214, Number 1: 7-12(6).
Rainbow Sensor & NDERainbow Sensor & NDE
5D0->7F1 5D0->7F2
Extract from: M. Gentleman and D. R. Clarke
Choice rare earth elements:Choice rare earth elements:
Weakly coupled tothe crystal field andlattice (‘f’ orbital)
Eu is a good candidate for hightemperature
Simplified Dieke Diagram of RE3+
Lifetime measurementsLifetime measurements
Optical set-up for calibration in temperature
Laser (Q-switch)Nd:YAG (532 nm)
furnaceFilters (+spectrometer)
PMT
PC
collection rodfibre
sample9 ns pulse (10Hz)
trigger
Lifetime decay of Eu 5D0-> 7F2 (606 nm) in YSZLifetime decay of Eu 5D0-> 7F2 (606 nm) in YSZ
Lifetimedecay
(Log)
(spontaneous emission)
Will be treated later
Lifetime decay of Eu 5D0-> 7F2 (606 nm) in YSZLifetime decay of Eu 5D0-> 7F2 (606 nm) in YSZ
Constant Vacancy Concentration
IncreasingStabilizerConcentration
Four levels modelFour levels model
( )( ) kT)/E(-expγ*/1=w
ww/1r.n
r.nRad
∆+=τ4 levels system supposing no temperature
dependence of parameters E/kT)(-exp)N(n.r)/N(f ∆=
γ = 2.4 10-13 s ∆E= 1.54 eV
Multi-Phonon Scattering Model(up conversion)
Multi-Phonon Scattering Model(up conversion)
( ) [ ]pK0TpRad 1nww/1 ++= =τ
( )[ ] 11/exp −−= kThn ν
n is the phonon occupancy factorv is the effective frequency of the
accepting phonon modep is the number of phonons needed to
bridge the energy gap between the excited state and the ground state
1/Wp(0K)=157 shν=0.0631 eVp=24.47 1.54 eV
Discussion: Layne and al. (1977), Multiphonon relaxation ofRare-earth ions in oxide glasses, Phys. Rev. B, 16#1 pp10-21
Multi-Phonon Scattering ModelFitting parameters
Multi-Phonon Scattering ModelFitting parameters
(unconstrained fit)
Current issues in calibrationsCurrent issues in calibrations
To get high intensity of luminescence of thin doping layers
High energy density of laser excitation
High concentration
(Room temperature, Chromium doped alumina)
Effect of high energy densityEffect of high energy density
Glan-thomsonpolarizer
Cr:Al2O3
Laser (532 nm)(pulse 9 ns)
Filters (spectrometer)
fibre
Polarizer changelaser density PMT
R-lines decays at different power densitiesR-lines decays at different power densities
Al2O3(0.07wt%[Cr])
Increase of LASERdensity
Multi-exponential transition spectroscopy (METS)Multi-exponential transition spectroscopy (METS)
Log derivative dI(t)/dln(t)
3 lifetime decays:
Spontaneous emissionFast decay (induced transition?)Long decay (multiple electron excitation?)
Gutierrez-Osuna, R., A. Gutierrez-Galvez, et al. (2003) “Transient response analysis for temperature-modulated chemoresistors”, Sensors and Actuators B 93: 57-66.
Effect of concentrationEffect of concentration
laser
luminescence
Cr
laser
Reabsorption
Energy Transfer Cr
luminescence
Experimental set-upExperimental set-up
Solid State Laser (26 mW*1ms)
Effect of reabsorptionEffect of reabsorption
Single crystal
Objective magnification
~1 cm
No objective
An increase of optical path increases lifetime values
Effect of reabsorptionEffect of reabsorption
Polycrystalline alumina
Difference of lifetime between 2 objective magnifications
objx100
Lifetime depends on:
Geometry of the set-upConcentrationThickness layer and
porosityReabsorption Coefficient in
Temperature
Include uncertainty on lifetime determination
Decay on highly doped aluminaDecay on highly doped alumina
Highly Cr doped alumina presents a non-exponential decay: Manifestation of time dependant
Phenomenon:
Energy transfer :
eNN(t) )-(t/0
)t(P−= τ
eNN(t)1/)-(t/
0
γτ= P(t) ?
eNN(t)1/)-(t/
0
γτ=Very robust to use a stretch exponential decay:
ConclusionsConclusions
Measurement where performed on Eu-YSZ up to 1100°C and is a good candidate for high temperature thermometry.
We note that increase of energy of the laser increase fluorescence signal but others phenomenon occur.
Lifetime measurement depends on:• Geometry of the set-up • Concentration,• Temperature,• Thickness layer and porosity
Acknowledgements:University of California Santa Barbara, Office of Naval Research (MURI), HYPERCOAT, NSF-EU PROGRAMBourse ‘Lavoisier’ 2004 (Ministère des Affaires Etrangères)
Messages personnelsMessages personnels
• Limoges SPCTS (2006 post-doc)“Instrumentation du procédé d’élaboration Frittage SHS
par une caméra infrarouge rapide ” (ThermaCam SC3000)
– Spectro rapide (0.1-1 ms/barrette) vis-NIR, ImSpector?
• Japon+UCSB (2007-2010)– Cutting edge project…