Active Microwave Thermography of Debonding Defects in Radar-Absorbing Coatings: Effects of Thickness and Power

In this study, the impact of active microwave thermography (AMT) on defect detection in radar-absorbing coatings (RACs) was investigated. Based on AMT technology, the effect of coating thickness and microwave power on defect clarity and optimal heating time was experimentally examined. In addition, electromagnetic–thermal coupled simulations were employed to explain the underlying physical mechanisms. Results indicate that coating thickness influences the optimal heating time for AMT: thinner coatings require shorter heating times. However, thickness also alters the reflectivity of RACs, leading to different effects of microwave power on defect clarity. Therefore, in practical inspections, heating time and microwave power should be appropriately selected based on both coating thickness and reflectivity to balance detection efficiency and image quality.