Sodium dodecyl sulfate (SDS) intercalated Mg Al layered double hydroxides film to enhance the corrosion resistance of AZ31 magnesium alloy

MgAl layered double hydroxides (LDHs) films intercalated with nitrate, molybdate, and sodium dodecyl sulfate (SDS) were in situ fabricated on AZ31 magnesium alloy by a combination of co-precipitation and hydrothermal method. The morphology, chemical composition and structure of the LDHs films were characterized by SEM, EDS, XPS, XRD and FT-IR. The corrosion resistance of the LDHs films was investigated by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and hydrogen evolution tests. The results show that the three LDHs films are dense and uniform, and closely adhere to the magnesium substrates. The corrosion resistance of the LDHs films is ranked in order as follows: MgAl-MoO42−-LDHs < MgAl-NO3−-LDHs < MgAl-SDS-LDHs. The SDS intercalated LDHs film exhibits the best corrosion protection performance, attributed to the physical barrier effect of the dense film structure, anion-exchange capacity of LDHs, and the adsorption and cathodic inhibition of SDS anions.