Preparation And Corrosion Behavior Of Self-Healing Coating With Halloysite Nanotube Loaded Inhibitor

In the field of corrosion protection of marine structures,anticorrosive coating has been widely used for its advantages of good protection effect,simple preparation and low cost.In the process of coating and application,the coating is prone to local damage.In sea water,the exposed metal substrate suffer corrosion quickly,which makes the failure area of the coating expand,and then leads to more serious corrosion.In order to prolong the service life of coating,more and more attention has been paid to the intelligent self-healing coating.Adding the nanocontainer loaded with corrosion inhibitor into the coating,the prepared coating can release corrosion inhibitor to protect the metal substrate,when it is damaged.The corresponding self-healing coating has been concerned and become a hot issue in present research.In this paper,8-hydroxyquinoline(8-HQ)and 2-Mercaptobenzothiazole(MBT)were loaded into halloysite nanotubes(HNTs)under negative pressure and encapsulated by Cu-8-HQ and Cu-MBT complex stopper respectively.And then Cu-8-HQ@HNTs/epoxy coating and Cu-MBT@HNTs/epoxy coating were prepared by mixing Cu-8-HQ@HNTs or Cu-MBT@HNTs with epoxy.The releasing behavior of 8-HQ and MBT in water under different pH was investigated by UV-Vis spectrophotometer.The surface morphology,wettability and adhesion of coating were observed and determined by optical microscopy,sessile water droplet static contact angle and pull-off adhesion tester.And the corrosion resistance of epoxy coatings in3.5% NaCl solution was analyzed by electrochemical impedance spectroscopy(EIS).Results show that the prepared Cu-8-HQ@HNTs complex has a higher release rate in acidic environment than that in neutral and alkaline solution.And the Cu-8-HQ@HNTs can be evenly dispersed in the epoxy resin.The prepared Cu-8-HQ@HNTs epoxy coating has a smooth surface,reduced hydrophilicity,and undiminished adhesion.Compering with blank epoxy coating and 8-HQ@HNTs epoxy coating,the Cu-8-HQ@HNTs epoxy coating shows higher and more stable corrosion resistance.In the case of coating damage,the end stopper of Cu-8-HQ@HNTs can be dissolved due to the acidification of scratched coating edge zone,and 8-HQ can be released to protect the substrate,achieving self-healing effect.For the prepared Cu-MBT@HNTs complex,the encapsulated MBT can be released slowly under neutral and acid conditions,but rapidly in alkaline condition.Adding CuMBT@HNTs to the epoxy resin,it can also be evenly dispersed.The prepared CuMBT@HNTs epoxy coating has a smooth surface,reduced hydrophilicity,and undiminished adhesion.In the case of coating damage,Cu-MBT@HNTs in the coating can release MBT in response to the local alkalization caused by metal corrosion,and form a corrosion inhibitor film on the metal surface to achieve self-healing effect.