Research on the corrosion protection of in-situ prepared Li[sbnd]Al layered double hydroxides on AZ31 Mg alloy under standard atmospheric pressure and low temperature

This work successfully prepared Li[sbnd]Al LDHs coatings on AZ31 Mg alloy under standard atmospheric pressure and low temperature. The whole process did not require a hydrothermal autoclave reactor and high pressure. Electrochemical test results showed that the coating was able to provide good corrosion protection performance. The Li[sbnd]Al LDHs coatings provided a large low-frequency impedance on AZ31. When the treatment time was 24 h, the maximum |Z|_0.01Hz at pH = 12 was 5.14 × 10⁴ Ω∙cm², which is more than an order of magnitude higher than the |Z|_0.01Hz of 1.81 × 10³ Ω∙cm² for the bare sample. Under the same treatment conditions, the potentiodynamic polarization test results showed that the Li[sbnd]Al LDHs coated samples had a lower corrosion current density and a higher breakdown potential. The i_corr was 1.78 × 10⁻⁷ A/cm² and E_br was −0.82 V_SCE compared to the Mg substrate (i_corr of 1.13 × 10⁻⁵ A/cm² and E_br of −1.53 V_SCE). Additionally, Li[sbnd]Al LDHs coatings also had a significant inhibitory effect on cathodic hydrogen evolution, providing targeted protection to the cathodic areas.