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 vertical bar Z vertical bar(0.01Hz) at pH = 12 was 5.14 x 10(4) Omega center dot cm(2), which is more than an order of magnitude higher than the vertical bar Z vertical bar(0.01Hz) of 1.81 x 10(3) Omega center dot 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 x 10(-7) A/cm(2) and E-br was 0.82 VSCE compared to the Mg substrate (i(corr) of 1.13 x 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.