Nondestructive monitoring of metal surfaces corrosion by radiofrequency methods [using EM slow wave structure propagation]

This paper introduces a radiofrequency (RF) method for sensing the corrosion processes on metal surfaces. A sensor, based on the propagation characteristics of electromagnetic slow wave structures (SWS), has been designed and constructed. The method is based on the use of RF slow-wave structures, which have suitable propagation and skin-effect characteristics on metal surfaces. The details of the design parameters of the sensor are given and the signal processing to extract the useful information from the sensor has been discussed. The propagation characteristics of the SWS electromagnetic waves in the corroding metals have been investigated in detail and compared with the microwave techniques. Mathematical analysis is introduced to explain the behavour of the electromagnetic waves on corroding metal surfaces. The proposed sensor can also be applied to pipelines, tanks, and other industrial installations that have protective coats on their surfaces to monitor the thickness and effectiveness of these coats.