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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 4 — Feb. 15, 2010
  • pp: 3477–3486

Pulsed-terahertz reflectometry for health monitoring of ceramic thermal barrier coatings

Chia-Chu Chen, Dong-Joon Lee, Tresa Pollock, and John F. Whitaker  »View Author Affiliations

Optics Express, Vol. 18, Issue 4, pp. 3477-3486 (2010)

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Terahertz time-domain reflectometry was used to monitor the progress of a thermally grown oxide layer and stress-induced, air-filled voids at the interface of an Yttria-stabilized-zirconia ceramic thermal-barrier coating and a metal surface. The thicknesses of these internal layers, observed in scanning-electron-microscope images to increase with thermal-exposure time, have been resolved – even when changing on the order of only a few micrometers – by distinguishing not only increased delays in the arrival times of terahertz pulses reflected from this multilayer structure, but also changes in the width and shape of the pulses. These unique features can be used to predict the lifetime of thermal-barrier coatings and to indicate or warn of spallation conditions. The trends of the experimental results are also confirmed through Fresnel-reflection time-domain simulations.

© 2010 OSA

OCIS Codes
(320.7100) Ultrafast optics : Ultrafast measurements
(110.6795) Imaging systems : Terahertz imaging

ToC Category:
Imaging Systems

Original Manuscript: December 18, 2009
Revised Manuscript: January 29, 2010
Manuscript Accepted: January 29, 2010
Published: February 3, 2010

Chia-Chu Chen, Dong-Joon Lee, Tresa Pollock, and John F. Whitaker, "Pulsed-terahertz reflectometry for health monitoring of ceramic thermal barrier coatings," Opt. Express 18, 3477-3486 (2010)

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