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Depth-Penetrating Temperature Measurements of Thermal Barrier Coatings Incorporating Thermographic PhosphorsThermographic phosphors have been previously demonstrated to provide effective non-contact, emissivity-independent surface temperature measurements. Because of the translucent nature of thermal barrier coatings (TBCs), thermographic phosphor-based temperature measurements can be extended beyond the surface to provide depth-selective temperature measurements by incorporating the thermographic phosphor layer at the depth where the temperature measurement is desired. In this paper, thermographic phosphor (Y2O3:Eu) fluorescence decay time measurements are demonstrated to provide through-the-coating thickness temperature readings up to 1100 C with the phosphor layer residing beneath a 100 micron thick TBC (plasma-sprayed 8wt% yttria-stabilized zirconia). With an appropriately chosen excitation wavelength and detection configuration, it is shown that sufficient phosphor emission is generated to provide effective temperature measurements, despite the attenuation of both the excitation and emission intensities by the overlying TBC. This depth-penetrating temperature measurement capability should prove particularly useful for TBC diagnostics where a large thermal gradient is typically present across the TBC thickness. The fluorescence decay from the Y2O3:Eu layer exhibited both an initial short-term exponential rise and a longer-term exponential decay. The rise time constant was demonstrated to provide better temperature indication below 500 C while the decay time constant was a better indicator at higher temperatures.
Document ID
Document Type
Preprint (Draft being sent to journal)
Eldridge, Jeffrey I.
(NASA Glenn Research Center Cleveland, OH, United States)
Bencic, Timothy J..
(NASA Glenn Research Center Cleveland, OH, United States)
Allison, Stephen W.
(Oak Ridge National Lab. TN, United States)
Beshears, David L.
(Oak Ridge National Lab. TN, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2003
Subject Category
Inorganic, Organic And Physical Chemistry
Meeting Information
International Thermal Spray Conference 2003(Orlando, FL)
Funding Number(s)
OTHER: 22-713-82-52
OTHER: 22-714-92-06
Distribution Limits
Work of the US Gov. Public Use Permitted.
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