Can TBC porosity be estimated by non-destructive infrared techniques? A theoretical and experimental analysis

Experimental and theoretical analysis confirmed that, independently from the specific microstructural features of the TBC samples, the contactless photothermal techniques allow to non-destructively estimate the porosity content with an overall uncertainty estimated theoretically as small as ± 5%. This uncertainty could result compatible with the requirements, especially for large porosity TBCs. Besides the uncertainty directly connected with the measurement, the uncertainty of the substrate effusivity, TBC specific heat and thickness contribute to the porosity estimation accuracy as well.