Terahertz characterization of interfacial oxide layers and voids for health monitoring of ceramic coatings

Terahertz time-domain reflectometry was used to monitor the progress of a thermally grown oxide layer and the resulting air-voids at the interface of an Yttria-stabilized-zirconia ceramic coating and a conductive metal surface. Experimental terahertz-pulse delays were compared to time-domain simulations and scanning-electron-microscope images.