NTRS - NASA Technical Reports Server

Back to Results
Nondestructive Evaluation of Thermal Barrier Coatings by Mid-infrared ReflectanceThe application of mid-infrared reflectance (MIR) imaging to monitor damage in thermal barrier coatings (TBCs) has been extended from a previously demonstrated area-averaged spectroscopic analysis tool to become a practical imaging tool that provides the spatial resolution needed to quickly identify localized regions of TBC damage by visual inspection, Illumination optics and image collection procedures were developed to produce illumination-normalized flatfield reflectance images after subtraction of the background thermal emission. MIR reflectance images were collected with a bandpass filter centered at a wavelength of 4 microns, which provided the optimum balance between good sensitivity to buried cracks and coating erosion, but with a desirable sensitivity to TBC sintering and absorption from ambient gases. Examples are presented of the application of MIR reflectance imaging to monitor damage progression in plasma-sprayed 8wt% yttria-stabilized zirconia (8YSZ) TBCs subjected to either furnace cycling or alumina particle jet erosion. These results show that MIR reflectance imaging can reliably track the progression of buried delamination cracks produced by thermal cycling and can also be used to determine when any local section of the TBC has eroded beyond an acceptable limit. Modeling of the effects of buried cracks and erosion on reflectance will be presented to show the dependence of damage sensitivity to TBC thickness.
Document ID
Acquisition Source
Glenn Research Center
Document Type
Preprint (Draft being sent to journal)
Eldridge, Jeffrey I
(NASA Glenn Research Center Cleveland, OH, United States)
Spuckler, Charles M.
(NASA Glenn Research Center Cleveland, OH, United States)
Nesbitt, James A.
(NASA Glenn Research Center Cleveland, OH, United States)
Martin, Richard E.
(Cleveland State Univ. Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
January 7, 2005
Subject Category
Quality Assurance And Reliability
Meeting Information
Meeting: 29th International Conference on Advanced Ceramics and Composites
Location: Cocoa Beach, FL
Country: United States
Start Date: January 23, 2005
End Date: January 28, 2005
Distribution Limits
Work of the US Gov. Public Use Permitted.
No Preview Available