Synergistic effects of ionic concentration and AC interference on accelerated corrosion testing of underground copper cables

The corrosion of buried copper-core cables at insulation defects poses a critical threat to underground infrastructure, yet conventional field exposure tests are impractically lengthy for timely assessment. This study develops a rapid and reliable accelerated corrosion testing protocol by systematically investigating the individual and synergistic effects of ionic concentration and alternating current (AC) interference. The study was conducted under four distinct conditions including regular simulation solution (RSS) as the baseline, RSS with AC interference (RSS + AC), aggressive simulation solution with tenfold ionic concentration (ASS), and the synergistic ASS + AC condition. Comprehensive characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical techniques revealed distinct corrosion behaviors. AC interference prevented the formation of stable protective oxide layers and induced continuous surface activation, resulting in a 25-fold increase in corrosion rate relative to RSS baseline. Increased ionic concentration promoted localized attack and thinned the protective layer, yielding a 9.4-fold acceleration relative to ASS baseline. Notably, the ASS + AC condition produced the most severe corrosion damage with basin-like morphology and the lowest electrochemical impedance, demonstrating a strong synergistic effect. These findings provide critical guidance for developing corrosion risk assessment methodologies for underground cable infrastructure.