Preparation of one-step organic anion-modified MgAl-LDH films under mild conditions for Mg alloy corrosion protection

The chelator-assisted method is considered to be an effective strategy for the in-situ growth of layered double hydroxide (LDH) films on magnesium alloy at atmospheric pressure. In this study, two organic anions, 2-Mercaptobenzothiazole (MBT) and sodium dodecyl benzene sulfonate (SDBS), were introduced separately during the synthesis of LDH films by chelator-assisted method to complete the organic modification of LDH films. The results demonstrated that the two organic anions promoted the growth of LDH in distinct forms. MBT could form an insoluble organic complex layer on the surface of LDH films, thereby enhancing their structural stability. The long carbon chain structure of the SDBS anion was successfully inserted into the LDH interlayer, resulting in a self-sealing microstructure and enhancing hydrophobicity of the LDH films. Both anions achieved by one-step preparation of organically modified LDH films on AZ31B magnesium alloy. The electrochemical test results showed that the modified LDH films had higher impedance modulus in the low-frequency region (|Z| LDH-SDBS (1.15 × 10 6 Ω cm 2 ) >|Z| LDH-MBT (8.58 × 10 5 Ω cm 2 ) >|Z| MgAl-LDH (4.09 × 10 5 Ω cm 2 )), which improved the corrosion resistance of the LDH films.