Research On The Construction Of Multifunctional Integrated Coating On The Surface Of Magnesium Alloy

Magnesium alloy has light weight,high specific strength and rigidity,good electrical and thermal conductivity,and excellent electromagnetic shielding properties,and has been widely used.However,magnesium alloy is currently a material with poor corrosion resistance among engineering materials,which severely limits its wide application and promotion.Soft texture and a magnesium alloy,although the beneficial cutting,but poor wear resistance,the study has a Mg alloy wear and corrosion resistance,and to provide long-term service of its excellent coating has been urgent.Although epoxy coating has excellent wear resistance and corrosion resistance,and low cost,it will shrink when the epoxy resin is cured,which will cause defects such as pores and cracks in the coating.As it is exposed to corrosive media As time increases,the width and depth of these defects will increase,thereby accelerating the corrosion process,so a single epoxy resin coating cannot provide long-term protection for magnesium alloys.Studies have found that adding some nanoparticles that tend to fill in the tiny defects generated during the curing and shrinking of epoxy resin can reduce the defect space and increase the crosslinking density of the epoxy resin layer.Therefore,this topic adds modified nano SiO₂to block the corrosion of the medium.Diffusion path in the epoxy resin matrix,thereby enhancing the corrosion resistance of the coating itself.Graphene oxide can play a good barrier in the coating.Therefore,this project prepared EP,EP/SiO₂,EP/GO,EP/GO/SiO₂coatings,with the help of metallographic microscope(OM),scanning electron microscope(SEM),atomic force microscope(AFM),Fourier infrared spectrometer(ATR-FTIR)characterize the influence of the microstructure;use the electrochemical workstation to analyze the corrosion resistance and long-term serviceability of each coating;use the surface wetting angle meter to measure the water contact angle of the coating;use the high-temperature friction and wear test The machine conducts tribological experiments on the coating,and uses real-color laser confocal microscope to characterize the wear of the coating.The main results obtained are as follows:(1)KH560 is used to modify nano-SiO₂and prepare EP/SiO₂coating.Compared with EP coating,this coating improves the flatness of the coating surface morphology.A three-dimensional network structure is formed inside the coating,which improves the compactness of the EP coating.The self-corrosion current of the magnesium alloy sample coated with the composite coating is reduced by 4 orders of magnitude;the corrosion rate is reduced by 5 orders of magnitude.In terms of long-term serviceability of the layer,after the EP/SiO₂coating was immersed in 3.5 wt%Na Cl solution for 14days,no corrosive medium diffused inside the coating.The hydrophobic angle is increased to 66.8°,the wear scar width is reduced by 85.6%compared with pure magnesium alloy,the depth is reduced by 77.9%,and the wear volume is reduced by94.5%.(2)The EP/GO coating was prepared by the layer-by-layer self-assembly method.The epoxy resin coating surface with GO became flat,and the cross-sectional defects disappeared.The corrosion resistance of the coating was qualitatively improved,which fully reflects the graphene oxide.Excellent corrosion resistance,but long-term serviceability.Because the galvanic corrosion of GO between the magnesium alloy substrates is reduced,the dispersion of GO needs to be improved,the hydrophobicity is58.5°,the wear scar width is 63.5%lower than that of the pure EP coating,and the depth is reduced 63.4%,the wear volume is reduced by 84.6%.(3)The EP/GO/SiO₂coating is prepared,and the graphene oxide flakes inside the coating are stretched out,which provides the coating with good barrier properties,excellent corrosion resistance and long-term service performance,and the hydrophobic angle is increased to 84.4°.The wear scar width of the layer is 4%larger than that of the EP/GO coating,the wear scar depth is 28.5%larger,and the wear volume is 70.6%higher;the wear scar width is 80.2%lower than that of the magnesium alloy,the wear scar depth is 88.7%smaller,and the wear volume is lower 70.6%.