Self-healing Properties Of Epoxy Coating Containing Amino Acid Intercalated Ldhs On Mg Alloy

Coatings used to inhibit metal corrosion inevitably produce microcracks during use,microcracks are inevitably generated,which in turn causes corrosion of the metal,which causes the coating to lose its protective effect and seriously shortens the service life of the coating.By adding a nanocontainer containing a corrosion inhibitor to the coating to achieve a self-healing epoxy coating,this problem can be effectively solved,resulting in long-lasting protection of the coating.In this paper,environmentally friendly amino acids were used as inhibitors,and they were intercalated into the Mg/Al layered double hydroxides(LDHs)layer by co-precipitation to prepare nanocontainers with controlled release function.The resulting nanocontainer was also added to the coating to investigate its self-healing properties.The research in this paper mainly includes the following aspects:Methionine was intercalated into the Mg/Al layered double hydroxides(LDHs)layer by co-precipitation method,which was released in a 0.35%NaCl solution and characterized by the corresponding technique.The results showed that methionine intercalated between the hydrotalcite layers can exchange with chloride ions in the electrolyte solution.The prepared methionine-intercalated LDHs was stirred and released under neutral,alkaline and acidic conditions,respectively,and the obtained extraction solution was impregnated with the Mg alloy to investigate the corrosion resistance of the released solution.The prepared methionine-intercalated LDHs was added to the epoxy coating,immersed in a 3.5%NaCl solution and tested accordingly.The results showed that the low-frequency impedance of the epoxy coating containing methionine-intercalated LDHs was maintained at 211 MΩ·cm~2 after immersion for85 days,indicating good self-healing properties.Combined with potentiodynamic polarization,EIS measurement and surface topography,the corrosion resistance mechanism of methionine-intercalated LDHs was proposed.The cysteine-intercalated Mg/Al LDHs nanocontainer was prepared by co-precipitation method,and the release experiment was carried out to investigate the release process of cysteine-intercalated Mg/Al LDHs nanocontainer in 0.35%NaCl solution.The low frequency impedance value of the magnesium alloy imersed in the cysteine-intercalated Mg/Al LDHs nanocontainer extraction solution reached a maximum after 24 hours of immersion,which was attributed to the faster self-healing performance of the cysteine-intercalated Mg/Al LDHs nanocontainer.The prepared nanocontainer was added to an epoxy coating and mimersed in a3.5%NaCl solution and tested accordingly.After the coating was immersed for 65 days,the low-frequency impedance of the coating reached 695 MΩ·cm~2.The co-precipitation method was used to intercalate histidine into the hydrotalcite layer,and the release of the histidine-intercalated LDHs nanocontainers by the release experiment combined with the corresponding technique was replaced by ion exchange by the chloride ion in the electrolyte solution.come out.The corrosion resistance of the Mg alloy immersed in the histidine-intercalated LDHs nanocontainers extraction solution was studied and tested by EIS.The prepared nanocontainers was added to the epoxy coating to study its self-healing performance.The results show that the epoxy coating containing the histidine-intercalated LDHs nanocontainers has good corrosion protection performance.The results show that the epoxy coating containing the histidine-intercalated hydrotalcite nanocontainer has good active corrosion protection performance,and the low-frequency impedance value after 75 days of immersion is still maintained at a high level.