Infrared thermal wave detection of interfacial debonding defects of thermal barrier coatings based on non-linear frequency modulation

In order to improve the reliability of detecting debonding defects at interface thermal barrier coatings (TBC), a non-linear frequency modulated (NLFM) infrared wave detection method is proposed. A NLFM system built, and zirconia TBC specimens are prepared tested. The effects defect diameter, excitation power, initial termination on effect analyzed. Three algorithms such as principal component analysis (PCA) used process image sequence, signal-to-noise ratio (SNR) each sequence processing algorithm calculated compared. results show that larger diameter defect, easier it be detected, appropriate adjustment power or reduction frequencies beneficial defects. Compared with other two algorithms, PCA more effective for processing. It offers reference flaws interface.