Non-destructive microwave detection of layer thickness in degraded thermal barrier coatings using K- and W-band frequency range

M. Sayar, D. Seo, K. Ogawa

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

Thermal barrier coatings have been widely used in gas turbine engines in order to protect the substrate metal alloy against high temperature and to enhance turbine efficiency. To monitor thermal barrier coating (TBC) integrity over its lifetime, the detection of top coat (TC) and thermally grown oxide (TGO) thicknesses was carried out using a microwave non-destructive technique. The results showed a good resolution of 1° change in phase for 15 μm TC thickness when a rectangular waveguide operating at relatively high frequency was applied. The phase of the reflection coefficient at the interface of TC and waveguide varies for different TGO and TC thicknesses. Therefore, measuring the phase of the reflection coefficient enables us to accurately calculate these thicknesses. Finally, a theoretical analysis was used to evaluate the reliability of the experimental results.

Original languageEnglish
Pages (from-to)398-403
Number of pages6
JournalNDT and E International
Volume42
Issue number5
DOIs
Publication statusPublished - 2009 Jul 1

Keywords

  • Microwave NDE
  • Thermal barrier coating
  • Thermally grown oxide

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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