A direct method for the simultaneous characterization of thermal diffusivities of a bi-layer material consisting of a thin coating deposited on a substrate

This work presents a method dedicated to the simultaneous identification of thermal diffusivities coatings or thin film materials. To ensure non-destructive characterization coating, present also implies substrate properties, which may be orthotropic. The estimation is based on resolution an inverse problem by minimizing quadratic difference between response 3D semi-analytical model and measurements resulting from single ‘3D flash method’ type experiment, using stochastic optimization algorithm. A unique non-intrusive test, that consists in recording temperature change cartography one face sample means infrared camera, required. evolution temperatures within material generated non-uniform almost instantaneous excitation imposed CO2 laser measured face. difficulties related control excitation, terms distribution flux energy absorbed material, are overcome estimating parameters associated simultaneously with diffusivities. developed applied estimate diffusivity coating used thermographic phosphor thermometry measure wall surface heat fluxes combustion environments. first evaluated simulated data as function measuring/excitation order feasibility, robustness accuracy current establish best experimental configuration. Experimental results then exploited compared other methods results.