Study On The Preparation And Self-healing Corrosion Mechanism Of MXene@LDHs Composite Films On Mg Alloy

Magnesium（Mg） and its alloys,possessing the advantages of low density,good casting property,high specific strength,good vibration and noise reduction and rich resources,are regarded as one of the inexhaustible lightest materials.However,the poor corrosion resistance significantly restricts the commercial applications of Mg alloys.Layered Double Hydroxides（LDHs）,which can be loaded as anion corrosion inhibitor between layers,is a common nano anticorrosion coating on Mg alloys.However,the loose nest-like morphology and structure characteristics of its growth perpendicular to the substrate Mg alloys surface,many tunnel gaps are built to reach the substrate during the growth process,which provide channels for the diffusion of corrosive species,resulting in poor corrosion resistance effect.In order to optimize the structure of LDHs,a composite film based on MXene@Mg Al-LDHs was constructed on the surface of commercial as-cast AZ31 magnesium alloy to improve the corrosion and protection performance of LDHs coating.Work 1:The trivalent rare earth metal cation(Y³⁺)salt solution with corrosion inhibition property was mixed with 2D Mxene nanosheet solution with good barrier property,and the Y modified MXene@Mg Al-LDHs composite film was obtained through one-step hydrothermal reaction by adjusting parameters such as p H temperature and time,and the film formation principle and corrosion mechanism of the composite coating were proposed.Work 2:Using the method of layer by layer assembly,PEI/Mxene was assembled and constructed on the Mgal-LDHs film loaded with V₂O₇^4-corrosion inhibitor to form multiple protection mechanisms,optimize the structure of the film and improve the corrosion resistance.This paper laid a foundation for the application of MXene nanomaterials in the field of metal corrosion and protection.In this paper,using the scanning electron microscope（SEM）,atomic force microscope（AFM）transmission electron microscope（TEM）,X-ray diffraction（XRD）,Fourier infrared spectrometer（FT-IR） glow discharge optical emission spectrometer（GDOES）,X-ray photoelectron energy spectrum analyzer（XPS）for structure and morphology characterization of sample Electrochemical experiment for hydrogen evolution scratch experiments such as the corrosion properties of the coating was tested characterization of the experimental results show that the electronegative MXene nanosheet mainboard can effectively adsorb cations in the reaction solution,which can promote the nucleation and growth of Mgal-LDHs and Y（OH）₃.As a connector,Mxene nanosheets loaded with Y（OH）₃ grow in situ on the surface of magnesium alloy AZ31.Y modified MXene@Mg Al-LDHs composite film has excellent anti-corrosion performance and good self-repair ability.Through the experimental results show that the two layers of assembly,the structure of the nests LDHs nano piece was completely covered（PEI/MXene）layer,the two-dimensional MXene materials can effectively prevent erosion corrosion medium,when and only when the assembly layer number n=10 the corrosion resistance of composite coating,the strongest when n≥20 layer,the outermost layer due to the micro cracks with the increase of the surface stress,resulting in a decline in protection.