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Towards Rapid, in Situ Monitoring of Thermal Barrier Coating Degradation Using Eddy Current NDE Technique
Published in Springer Science and Business Media Deutschland GmbH
Pages: 9 - 21
Aircraft components exposed to high temperature are usually coated with an insulating layer to protect them from failure due to thermal fatigue. This thin layer, known as thermal barrier coating (TBC), has to be monitored regularly in order to check for its degradation and loss of thickness during operation. Inspection of such components poses a challenge owing to the chemical composition, unevenness, and porous nature of the coating. In this paper, the authors propose a methodology for the feasible implementation of the eddy current technique in order to perform a high-speed inspection of thermal barrier-coated components and evaluate their condition. A set of reference specimen with predetermined TBC thickness values is used for the trials. After preliminary simulation studies to select the optimum parameters, raster scanning is performed on the specimen using an experimental configuration assembled in-house. The results show a variation in TBC thickness within each specimen, which are validated using measurements from the THz time-domain spectroscopy (TDS) method. A thickness map of each specimen is generated after cross-correlation. Furthermore, this eddy current-based approach is implemented for quantitatively evaluating the condition of another batch of TBC samples that were subjected to varying in-service conditions. With a robust setup and proper calibration procedure, the proposed methodology has the potential to be implemented for the fast and reliable inspection of aircraft engine components to ensure structural integrity. © 2022, Indian Society for Non-destructive Testing.
About the journal
JournalLecture Notes in Mechanical Engineering
PublisherSpringer Science and Business Media Deutschland GmbH