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

This work successfully prepared Li 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 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 × 10 ⁴ Ω∙cm ², which is more than an order of magnitude higher than the |Z| _0.01Hz of 1.81 × 10 ³ Ω∙cm ² for the bare sample. Under the same treatment conditions, the potentiodynamic polarization test results showed that the Li Al LDHs coated samples had a lower corrosion current density and a higher breakdown potential. The i _corr was 1.78 × 10 ⁻⁷ A/cm ² and E _br was −0.82 V _SCE compared to the Mg substrate ( i _corr of 1.13 × 10 ⁻⁵ A/cm ² and E _br of −1.53 V _SCE). Additionally, Li Al LDHs coatings also had a significant inhibitory effect on cathodic hydrogen evolution, providing targeted protection to the cathodic areas.