A comparative study and optimization of corrosion resistance of Mg–Al layered double hydroxides films at different hydrothermal temperatures on LA103Z Mg–Li alloy

Abstract

In this study, to improve the corrosion protection system of Mg-Li alloy, Magnesia-alumina Layered double hydroxide (Mg-Al LDH) films were prepared on the LA103Z magnesium-lithium (Mg-Li) alloy by the in situ hydrothermal method. Subsequently, the microstructure of the Mg-Al LDH films was characterized by scanning electron microscope, X-ray spectrometer, X-ray diffraction, Fourier-transform infrared spectroscopy, and the effect of different hydrothermal temperatures on the growth of the film was studied.Electrochemical impedance spectroscopy (EIS) and hydrogen evolution test were used to study the corrosion behavior of the films, revealing the anticorrosion mechanism of the films. The results show that the LDH film is in the form of a sheet-like structure that crosses vertically on the LA103Z substrate. With the increase of the hydrothermal temperature, the size of the Mg-Al LDH sheet increases, and the distribution is denser. Electrochemical tests showed that the coated samples had significantly improved impedance modulus (|Z|) and charge transfer resistance (R t ) compared to bare samples. The potentiodynamic polarization curves demonstrated that the Mg-Al LDH film can effectively improve the corrosion resistance of the LA103Z magnesium alloy substrate.corrosion mechanism, corrosion resistance, in situ hydrothermal method, LDH film, Mg-Li alloy | INTRODUCTIONRecently, magnesium (Mg) and its alloys have attracted much attention due to their high specific strength, excellent electromagnetic shielding properties, good casting properties, vibration-damping properties, good biocompatibility, and easy recycling. [1][2][3] These properties have good application prospects in the automotive, aerospace, communication electronics, and biomedical fields. [4,5] However, due to their high electrochemical activity, particularly in environments and solutions containing Cl − , where they are vulnerable to the aggression of Cl − , magnesium alloys have poor corrosion resistance, which severely restricts their use and