Corrosion behavior of conductor materials under various DC electric-field strengths in simulated marine atmospheres

Severe corrosion of high-voltage transmission lines in marine atmospheric environment is observed, significantly impacting the safety of power systems. This study systematically investigated the corrosion of Cu and Al alloy conductors under various DC electric-field strengths in high-humidity and chloride-containing environments. Electrochemical tests, corrosion products analysis, and morphological characterization collectively revealed that for both Cu and Al alloy materials, corrosion was minimal in the absence of an electric field, but the amount of surface corrosion products significantly increased upon application of an electric field. Electrochemical impedance spectroscopy reveals a decrease in charge transfer resistance as the electric field strength increases. Similarly, polarization curve analysis demonstrates a corresponding increase in corrosion current density with rising field strength. Further corrosion products analysis confirmed that the corrosion products of Cu is Cu2O, CuO, Cu2(OH)2CO3 and the corrosion products of Al alloy is AlO(OH), Al2O3. Moreover, pitting corrosion pit statistics indicated that at 400 kV/m, the maximum pitting corrosion depths for Cu and Al alloy were 2–3 times greater than those observed in the absence of an electric field. The overall corrosion rate of both materials exhibited a consistent increase with rising electric field strength. The electric field accelerates chloride-ion migration through the thin liquid film, facilitating film breakdown and localised corrosion.