Corrosion monitoring for transmission line based on electromechanical impedance instrumented circular piezoelectric corrosion sensor

Corrosion-induced thickness loss is a common form structural damage in transmission lines. In our previous work, a novel circular piezoelectric-metal transducer for corrosion sensing using the electromechanical impedance (EMI) technique was proposed. This transducer was fabricated by attaching a lead zirconate titanate (PZT) patch to a metal plate. In the present study, the piezoelectric-metal transducer was encapsulated and enhanced, and two types of corrosion sensors were developed: piezoelectric-steel and piezoelectric-zinc sensors. To assess the practical performance of the corrosion sensors, the piezoelectric-steel and piezoelectric-zinc sensors were connected to the angle steels and the steel strands, which are highly prone to corrosion in transmission lines. Corrosion monitoring experiments were conducted in the laboratory. The results demonstrate that the peak frequencies in the conductance signatures decrease linearly with increasing corrosion-induced thickness loss. Furthermore, it was found that piezoelectric-steel sensors are effective for quantitative monitoring of metallic corrosion, whereas piezoelectric-zinc sensors are better suited for early-stage corrosion monitoring and warning.