テラヘルツ波による耐熱コーティング材の非破壊評価

概要

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Terahertz (THz) wave propagation behavior for yttria partially stabilized zirconia (YSZ) thermal barrier coatings, which were fabricated by atmospheric plasma spray deposition, was investigated using terahertz time domain spectroscopy in the frequency range of 0.1 ~ 6.3 THz. YSZ coating showed good transmittance for the applied frequency range. The group refractive index was evaluated from the detected wave in the reflection measurement. It was found that the coating thickness can be easily measured by knowing the refractive index and that strong correlation between the porosity of the coatings and the refractive index exists. Also the THz wave measurement was performed for the delaminated portion of the YSZ coatings and the feasibility to detect the delamination was investigated. A clear difference was found between the waveforms detected on the delaminated and bonded areas. The results suggested that the THz technology may be a promising non-destructive evaluation (NDE) technique for the thick ceramic coatings such as thermal barrier coatings.
一般社団法人日本非破壊検査協会の論文