FIB-TEM characterizations of a novel corrosion-resistant and hydrophobic LDH–MA composite coating on WE43 alloys

An ecofriendly layered double hydroxide (LDH) organic-composite coating offers a new strategy for enhancing the corrosion resistance of WE43 magnesium alloys in aerospace applications. The internal structure of an organic intercalated LDH composite coated on magnesium alloys significantly enhances their hydrophobicity and corrosion resistance. Herein, a novel myristic acid (MA)-intercalated LDH composite coating was prepared on WE43 alloys. Microstructural analysis reveals that the defects generated during the oxidation process are repaired through the formation of LDH nanosheets and LDH–MA composite coatings via MA intercalation. Focused ion beam–transmission electron microscopy and electrochemical tests show that the high corrosion resistance (corrosion inhibition efficiency >99.9 %, polarization resistance = 1.9 × 10⁷ Ω·cm²) of the LDH–MA composite coating is due to the protective barriers of the dense LDH sheets, the high hydrophobicity of the composite coating, the inhibition effect of MA anions released from the LDH interlayer, and the re-adsorption of the overflowed MA anions into the LDH interlayer. Compared to the uncoated bare alloy, the impedance value of the LDH-MA composite coatings increases by four orders of magnitude, and the static water contact angle rises from 25.8° to 141.9°. Moreover, the corrosion resistance mechanism of LDH–MA composite coatings was discussed.