An investigation into atmospheric corrosion detection under paint with K-band microwave NDT

Microwave based technique plays a vital role in non-destructive testing (NDT) field. A microwave based NDT method has been developed to detect and evaluate atmospheric corrosion under paint. The results are promising, the measurement sensitivity and resolution of microwave NDT can be significantly improved with known the lift-off (air layer) in the corrosion detection applications. The aim of this investigation was achieved by using electromagnetic computer simulation technology (CST 2012) describing the interaction of microwave signals radiated out of an open-ended rectangular waveguide with a layered medium. This CST program calculates the reflection coefficient (simulating corrosion measurements), and describes the field distribution in multiple layered media. Steel sample with 12 months exposure time has been measured. The experimental results were obtained by using a microwave NDT scanning system that was built according to the results of the theoretical investigation, and they confirmed the theoretical results.