Non-destructive thickness measurement of thermal barrier coatings using terahertz radiation

Abstract A non-destructive thickness measurement technique based on terahertz (THz) reflectivity was successfully deployed to interrogate 7 wt.% yttria-stabilised zirconia thermal barrier coatings (TBCs) produced by electron-beam physical vapour deposition (EB-PVD). The THz shown produce accurate maps for different samples with a resolution of 1 × mm over surface 65 20 that were compared direct examination key cross-sections. All measurements calculated using single value refractive index. Small defects characteristic EB-PVD, such as “carrot growths” and variations column inclination, evaluated did not significant in the index TBC. Moreover, correctly display are consequence point-source nature EB-PVD evaporation. In summary, this paper demonstrates can be large surfaces, across same material under conditions. It is n required map distribution all samples. This combination qualities indicates potential in-line control TBC manufacture.