15. Nondestructive Evaluation of Thermal Barrier Coatings by Mid-Infrared Reflectance Imaging

  1. Dongming Zhu and
  2. Kevin Plucknett
  1. Jeffrey I. Eldridge1,
  2. Charles M. Spuckler1,
  3. James A. Nesbitt1 and
  4. Richard E. Martin2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291238.ch15

Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3

Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3

How to Cite

Eldridge, J. I., Spuckler, C. M., Nesbitt, J. A. and Martin, R. E. (2005) Nondestructive Evaluation of Thermal Barrier Coatings by Mid-Infrared Reflectance Imaging, in Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3 (eds D. Zhu and K. Plucknett), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291238.ch15

Author Information

  1. 1

    NASA Glenn Research Center 21000 Brookpark Rd. Cleveland, OH 44135

  2. 2

    Cleveland State University Cleveland, OH

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982336

Online ISBN: 9780470291238

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Keywords:

  • spectroscopic;
  • thermal;
  • MIR;
  • parabolic;
  • environments

Summary

The 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 flatfleld 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 insensitivity 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 MTR 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.