Impact of wet-dry cycle on the corrosion of grounding down leads in saline soil

Abstract

This study investigates the corrosion behaviour of grounding down leads in transmission towers subjected to wet–dry cycle in saline soils of Northwest China through accelerated corrosion experiments. Using saline soil from the Hexi Corridor, rich in chloride and sulphate ions, corrosion rates were assessed via weight loss, polarisation curves, scanning electron microscopy and X-ray diffraction analyses. Results demonstrate that wet–dry cycle significantly accelerates corrosion due to enhanced chloride ion diffusion and corrosion kinetics, with the highest average weight loss rate (3.08%) and corrosion current density (0.3526 mA/cm²). Scanning electron microscopy analysis revealed extensive cracking in corrosion product layers under cyclic wet–dry conditions, weakening their protective capability and further intensifying corrosion. The primary corrosion products identified were FeO and Fe₂O₃, consistent with field samples, indicating that the corrosion mechanism remains unchanged under accelerated conditions. This study provides novel insights into how cyclic moisture conditions affect grounding materials in saline environments, guiding material selection, maintenance strategies and site selection to improve transmission line reliability and safety.