Corrosion Inhibition Behavior of Aluminum Alloy by EDTA Sodium Salts in Simulated HVDC Internal Cooling Water

ABSTRACT Aluminum radiators in converter valve systems of high‐voltage direct current (HVDC) transmissions are prone to corrosion under the coupled effects of multiple physical fields. The resulting Al 3+ deposit on the grading electrode surface can lead to serious safety incidents. In this study, ethylenediaminetetraacetic acid disodium (EDTA‐2Na), trisodium (EDTA‐3Na), and tetrasodium (EDTA‐4Na) salts are employed as corrosion inhibitors, and 10 mM HCl is used to simulate the acidic environment formed on aluminum radiator surfaces under high electric potential. The corrosion inhibition behavior of aluminum in the electrolyte was systematically investigated. The results showed that the inhibition efficiencies of 5 mM EDTA‐2Na, 3 mM EDTA‐3Na, and 1 mM EDTA‐4Na reached 99.09%, 99.10%, and 98.70%, respectively. The differences in inhibition performance were mainly attributed to variations in solution pH induced by different numbers of sodium ions, which altered the predominant EDTA species in solution. Furthermore, the adsorption configurations of the inhibitors on the aluminum surface were analyzed using physical characterization techniques and theoretical calculations.