Thermal conductivity measurement of EB-PVD thermal barrier coatings using an infrared transparent substrate

초록

Electron beam physical vapor deposition (EB-PVD) thermal barrier coatings (TBCs) exhibit microstructural evolution with increasing coating thickness, resulting in thickness-dependent thermal conductivity. To obtain reliable thermal conductivity data within the practical thickness range for gas turbine applications (approximately 100-150 & micro;m), an accurate measurement approach is required. In this study, laser flash analysis (LFA) was investigated to evaluate the thermal conductivity of EB-PVD coatings. The conventional bilayer configuration using metallic substrates was first examined, revealing measurement limitations due to substrate interference. To address this issue, an infrared-transparent single-crystal sapphire substrate was employed to enable direct measurement of the coating thermal properties. Using this approach, reliable thermal conductivity data for EBPVD YSZ coatings approximately 150 & micro;m thick were obtained. The results confirm that the proposed method enables accurate determination of the intrinsic thermal conductivity of EB-PVD coatings within the applicable thickness range.

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