Estimating thermal properties of coatings by using multi-frequency lock-in thermography

Ceramic thermal barrier coatings (TBCs) play a crucial role in protecting components exposed to combustion gases or high temperature. However, TBCs can degrade over time due to thermal/mechanical fatigue and chemical processes, highlighting the importance of monitoring sintering kinetics. Changes in thermal diffusivity are indicative of sintering progression, necessitating precise and efficient evaluation methods. To this aim, pulsed and lock-in thermography are established techniques, but face limitations such as SNR constraints and the need for multiple tests at single frequencies. To address these challenges, a novel approach called Multi-frequency (MF) lock-in thermography is here introduced. While further research is required for achieving results comparable to state-of-the-art techniques, this study show promises for MF thermography in characterizing TBC properties.