Nondestructive testing (NDT) of thermal barrier coating (TBC) systems is a critical issue in their manufacturing environments. In particular, inspection techniques by which thickness of TBC topcoat can be accurately determined are currently being sought. This work investigates the use of open-ended rectangular waveguide probes at frequencies in the range of 26.5-70 GHz for evaluation of TBC topcoat thickness. In addition, the influence of volumetric porosity level on thickness measurement accuracy is considered. This investigation encompasses electromagnetic modeling and experimental efforts that are shown to result in the ability to estimate topcoat TBC thickness to within ±1 mil.
 N. P. Padture, M. Gell, and E. H. Jordan, “Thermal Barrier Coatings for Gas-Turbine Engine Applications,” Science, vol. 296, no. 5566, pp. 280–284, Apr. 2002, doi: 10.1126/science.1068609.
 A. J. K. M. Firdaus, R. Sloan, C. I. Duff, M. Wielgat, and J. F. Knowles, “Microwave nondestructive evaluation of thermal barrier coated turbine blades using correlation analysis,” in 2016 46th European Microwave Conference (EuMC), Oct. 2016, pp. 520–523. doi: 10.1109/EuMC.2016.7824394.
 S. Parthasarathi, B. R. Tittmann, and E. J. Onesto, “Ultrasonic technique for measuring porosity of plasma-sprayed alumina coatings,” J. Therm. Spray Technol., vol. 6, no. 4, pp. 486–488, Dec. 1997, doi:
 B. Cao, E. Cai, and M. Fan, “NDE of Discontinuities in Thermal Barrier Coatings with Terahertz Time-Domain Spectroscopy and Machine Learning Classifiers,” Mater. Eval., vol. 79, no. 2, pp. 125–135, Feb. 2021, doi: 10.32548/2021.me-04189.
 G. N. Jawad and M. F. Akbar, “IFFT-Based Microwave Non-Destructive Testing for Delamination Detection and Thickness Estimation,” IEEE Access, vol. 9, pp. 98561–98572, 2021, doi:
 X. Q. Cao, R. Vassen, and D. Stoever, “Ceramic materials for thermal barrier coatings,” J. Eur. Ceram. Soc., vol. 24, no. 1, pp. 1–10, Jan. 2004, doi: 10.1016/S0955-2219(03)00129-8.
 J. Sebastian, A. Scaria, and D. G. Kurian, “Development & characterization of alumina coating by atmospheric plasma spraying,” IOP Conf. Ser. Mater. Sci. Eng., vol. 330, p. 012043, Mar. 2018, doi: 10.1088/1757-899X/330/1/012043.
 M. T. Lanagan, J. K. Yamamoto, A. Bhalla, and S. G. Sankar, “The dielectric properties of yttria-stabilized zirconia,” Mater. Lett., vol. 7, no. 12, pp. 437–440, Mar. 1989, doi: 10.1016/0167-577X(89)90047-5.
 J. Gao, X. Xiong, and Y. Gao, “The effect of the α/γ phase on the dielectric properties of plasma sprayed Al2O3 coatings,” J. Mater. Sci. Mater. Electron., vol. 28, no. 16, pp. 12015–12020, Aug. 2017, doi: 10.1007/s10854-017-7011-6.
 R. Zoughi, “Microwave non-destructive testing and evaluation,” 2000. doi: 10.1007/978-94-015-1303-6.
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