Nondestructive Tomographic Imaging of Rust with Rapid THz Time-Domain Spectroscopy

In this study, we developed a rapid nondestructive tool for testing rust spread in metal covered by paint layer using THz time-domain spectroscopy system at speed of 100 Hz/pixel. Time-of-flight imaging helps identify formation exclusively obtaining the reflection from steel below surface. The use frequency-selective allows us to manipulate contrast imaging. Higher is generally obtained when monitoring higher frequency component. addition, monitored plate under influence two different chemical solutions: NaCl and acid. We found that early stages, decrease was governed high-frequency components due lepidocrocite, whereas low-frequency component develops as proportion hematite increases with time.