Research Progress on LDHs@MXene Self-healing Composite Coatings

MXenes are highly promising materials for self-healing coatings on Mg alloys. The high aspect ratio of MXenes material ensures its excellent physical barrier performance, prolongs the invasion path of corrosive ions, and gives it excellent corrosion resistance. In our various studies, Y-modified MXenes/MgAl LDHs composite coatings were successfully grown in situ on AZ31 magnesium alloy by the hydrothermal method. Rare earth ions Y increase the compactness of the corrosion product film, and the composite coating shows a very low corrosion current density of 9.12×10^-9 A·cm^-2. MXenes are good carriers of corrosion inhibitors due to their high specific surface area. 4-aminophenol@MXenes are prepared and introduced onto MgAlLa LDHs via a low-temperature water bath method. The scratched composite P/MgAlLa LDHs-M@A coating exhibits approximate |Z|_{0.01 Hz} with unscratched samples even after 12 h corrosion. Outer (PEI/MXene)_n-based layers were assembled on the surface of MgAl-V₂O₇⁴⁻ LDHs film via the layer-by-layer (LbL) approach to further explore its physical barrier-blocking effect and protection mechanism for corrosion inhibition. In another study, electrophoretic deposition technology was further utilized to incorporate disordered MXenes onto the 2,5-Pyridinedicarboxylic acid (2, 5-PDCA)-modified ZnAl-LDHs coating. MXenes uniformly coated the 2,5 PDCA-LDH film, forming a protective barrier against corrosive species while simultaneously establishing a lubricating layer. Additionally, MXenes are applied as nanofiller to enhance the performance of epoxy resin (EP) coating, where the MXenes are modified with in situ grown ZnAl LDHs. The synergistic physical barrier effect of LDHs and MXenes effectively enhance the corrosion and wear resistance of EP coating.