In situ NDT of Degradation of Thermal Barrier Coatings Using Impedance Spectroscopy

Kazuhiro Ogawa, Tetsuo Shoji, Iwao Abe, Hideo Hashimoto

Research output: Contribution to specialist publicationArticle

9 Citations (Scopus)


Thermal barrier coating (TBC) is mandatory for hot section parts of advanced gas turbine plants, such as turbine blades, vanes, etc. However, degradation of TBC can take place due to long term operation at high temperature. The degradation is mainly caused by both microstructural changes and thermal stress as a result of reaction layer formation at the interface between the TBC and bond coating. Therefore, it is critical to detect the formation and quantitatively evaluate the growth rate of the reaction layers. In this study, a novel in situ NDT method is developed for characterization of the reaction layer formation and its growth kinetics. Formation kinetics and physical properties of the reaction layer are evaluated by impedance spectroscopy (IS) technique. Specimens were aged over a long period of time, which provides large impedance. The impedance behavior of TBC and bond coating change significantly with the formation and the growth of the reaction layer. This allows us to nondestructively test the detrimental effects of the presence of the reaction layer for TBC integrity at high temperature.

Original languageEnglish
Number of pages6
Specialist publicationMaterials Evaluation
Publication statusPublished - 2000 Mar


  • Alumina
  • Impedance spectroscopy
  • In situ NDT
  • Mixed oxide
  • Model analysis
  • Reaction layer
  • TBC/MCrAlY interface
  • Thermal barrier coating

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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