Collaborative corrosion inhibition behavior of sodium lauryl diphenyl ether disulfonate and Na2B4O7 on AZ91D magnesium alloy

This study investigated the collaborative corrosion inhibition behavior of sodium lauryl diphenyl ether disulfonate (SLDED) and Na₂B₄O₇ on AZ91D magnesium alloy in a 3.5 wt% NaCl solution at 30 °C, combining electrochemical experiments, surface characterization techniques, and theoretical calculations. The results showed that the corrosion inhibition efficiency of the compound corrosion inhibitor consisting of SLDED and Na₂B₄O₇ was significantly higher than that when they were used as a single corrosion inhibitor. When the concentrations of both SLDED and Na₂B₄O₇ were 5 g/L, the corrosion inhibition efficiency reached 87.50 %. This might be because the hydrophobic effect of adsorbed SLDED provided a guarantee for the complete precipitation of BO₂⁻, forming a dense insoluble borate precipitation film (MgBO₂(OH) + Mg₂B₂O₅), while the formation of the precipitation film induced by Na₂B₄O₇ could prevent the desorption of adsorbed SLDED and filled the tiny defects in the SLDED film, thereby enhancing the overall protective effect.