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Detecting Thermal Barrier Coating Delamination Using Visible and Near-Infrared Luminescence from Erbium-Doped SublayersNondestructive diagnostic tools are needed to monitor early stages of delamination progression in thermal barrier coatings (TBCs) because the risk of delamination induced coating failure will compromise engine performance and safety. Previous work has demonstrated that for TBCs composed of yttria-stabilized zirconia (YSZ), luminescence from a buried europium-doped sublayer can be utilized to identify the location of TBC delamination from the substantially higher luminescence intensity observed from the delaminated regions of the TBC. Luminescence measurements from buried europium-doped layers depend on sufficient transmittance of the 532 nm excitation and 606 nm emission wavelengths through the attenuating undoped YSZ overlayer to produce easily detected luminescence. In the present work, improved delamination indication is demonstrated using erbium-doped YSZ sublayers. For visible-wavelength luminescence, the erbium-doped sublayer offers the advantage of a very strong excitation peak at 517 nm that can be conveniently excited a 514 nm Ar ion laser. More importantly, the erbium-doped sublayer also produces near-infrared luminescence at 1550 nm that is effectively excited by a 980 nm laser diode. Both the 980 nm excitation and the 1550 nm emission are transmitted through the TBC with much less attenuation than visible wavelengths and therefore show great promise for delamination monitoring through thicker or more highly scattering TBCs. The application of this approach for both electron beam physical vapor deposited (EB-PVD) and plasma-sprayed TBCs is discussed.
Document ID
Document Type
Conference Paper
Eldridge, J. I.
(NASA Glenn Research Center Cleveland, OH, United States)
Bencic, T. J.
(NASA Glenn Research Center Cleveland, OH, United States)
Martin, R. E.
(Cleveland State Univ. Cleveland, OH, United States)
Singh, J.
(Pennsylvania State Univ. University Park, PA, United States)
Wolfe, D. E.
(Pennsylvania State Univ. University Park, PA, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2007
Subject Category
Composite Materials
Meeting Information
31st International Cocoa Beach Conference and Exposition on Advanced Ceramics and Composites(Daytona Beach, FL)
Funding Number(s)
WBS: WBS 5615810208.03.04.03
Distribution Limits
Public Use Permitted.
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