Effect of Seawater Corrosion on Aging Performance of Cross-linked Polyethylene Cable Insulation

Owing to the complex operation environment in the ocean, the external structure of submarine XLPE cable is vulnerable to damage, enabling seawater infiltration and subsequent irreversible degradation of the cable's insulation material. This study primarily seeks to clarify the effect of seawater corrosion on the aging performance of XLPE cable insulation. To this end, accelerated seawater corrosion samples are systematically examined through several aging evaluation methods, including SEM, FTIR, DSC, and AC electrical breakdown tests. Further, microscopic structural changes within the XLPE cable insulation during seawater corrosion are analyzed through molecular simulations. Ultimately, based on the above research results, the mechanism by which seawater corrosion contributes to the deterioration of cable insulation is elucidated and then a preliminary study on material modification is conducted. Test results indicate that there is a non-monotonic evolution of insulation performance with exposure time, characterized by an initial improvement followed by progressive deterioration. Increasing seawater concentration accelerates degradation but exhibits a clear saturation effect beyond a threshold. Furthermore, nanofiller incorporation, particularly Al2O3, significantly enhances insulation performance by reducing mass loss and suppressing corrosive species diffusion, which can provide some help in future research to improve the long-term durability of XLPE cable in the marine condition.