| Magnesium alloy has the advantages of high strength,low density,good plasticity and excellent biocompatibility.It is widely used in automotive,aerospace,3C products and biomedical fields.However,the electrochemical properties of magnesium alloy are relatively active and highly susceptible to corrosion,limiting the range of applications of magnesium alloy.Therefore,research on improving the corrosion resistance of magnesium alloy is very necessary for the application of magnesium alloy.The one of the common methods to reduce the magnesium alloy corrosion is prepared the anti-corrosion coating on the substrate surface.However,the change of coatings mechanical properties during service life will lead to the formation of cracks in its deep structure of coatings.The cracks propagation exposes the substrate to the corrosion matrix,the coating is destroyed eventually.It is very difficult to detect micron scale initial cracks,so it is almost impossible to repair the cracks artificially in time.Therefore,the research focus on the preparation of self-repairing anticorrosive coatings.In this paper,a self-repairing polydopamine / hydroxyapatite coating was prepared on the surface of AZ31 magnesium alloy to improve the corrosion resistance of magnesium alloy.The 2-mercaptobenzimidazole(MBI)is an efficient,low toxic and biodegradable imidazole reagent,which was selected as corrosion inhibitor.The inhibitor-loaded silica nanocontainers were doped into the composite coatings,and their corrosion resistance and self-repairing properties were studied.Firstly,mesoporous Si O2 nanoparticles were prepared by microemulsion method,and the corrosion inhibitor2-mercaptobenzimidazole(MBI)was loaded into mesoporous Si O2 particles under the decompression condition.Then the inhibitor-loaded silica nanocontainers was doped into polydopamine / Hydroxyapatite coating.SEM,TEM,XRD,BET and other methods were used to characterize the morphology,structure of mesoporous Si O2 nanoparticles and load situation of corrosion inhibitor.The composition and morphology of the coatings were characterized by FT-IR and SEM.The corrosion resistance and self-repair properties of different coatings were investigated by EIS and weight loss analysis.The results show that the as-prepared Si O2 has an uniform particle size,which possess an ordered mesoporous structure with a pore size of ~3 nm.The Si O2 nanoparticles can successfully support the corrosion inhibitor 2-mercaptobenzimidazole.The corrosion resistance and self-repairing properties of the coating could be improved by doping of the inhibitor-loaded silica nanocontainers into the polydopamine / hydroxyapatite coating.In order to reduce the cost and simplify the steps,the inhibitor-loaded silica nanocontainers were prepared in one-step by using the oil-in-water microemulsion method.The prepared inhibitor-loaded silica nanocontainers are doped into the polydopamine / hydroxyapatite coating.SEM,TEM,XRD and FT-IR were used to characterize the morphology,structure of mesoporous Si O2 nanoparticles and load situation of corrosion inhibitor.The release process of corrosion inhibitor MBI at different p H was studied by UV-vis;the composition and morphology of the coating were analyzed by FT-IR and SEM.EIS and weight loss analysis were used to study the corrosion resistance and self-healing properties of different coatings.The results show that as-prepared Si O2 has an uniform particle size in the experiment,witch can successfully support the corrosion inhibitor by one-step method.The release of MBI in mesoporous Si O2 particles is affected by p H value,and its release rate under acidic conditions is greater than neutral and alkaline conditions.This regular pattern is consistent with the relative corrosion rate of magnesium alloy under acid and alkaline conditions,which is beneficial to the corrosion protection of magnesium alloy.The corrosion inhibitor MBI is loaded into the mesoporous Si O2 nanoparticles,result the corrosion inhibitor is slowly released,the utilization efficiency is improved.The inhibitor-loaded silica nanocontainers doping into coating can improve the corrosion resistance and self-repairing of the coating. |
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