| Metal corrosion and protection is a major issue that people face today.In order to avoid the loss caused by metal corrosion effectively,people have adopted a variety of methods,among which anti-corrosion coating is the most widely used.The performance of anticorrosive coating is largely determined by the added anticorrosive pigments.However,the traditional anticorrosive pigments,such as hexavalent oxidizing chromate and pentavalent nonoxidizing phosphate,which have good corrosion inhibition effect,are gradually restricted due to their pollution to the environment.Therefore,it is necessary to develop new green anti-rust pigments.The previous studies have shown that VO43-released by vanadate in water could be absorbed onto the surface of aluminum alloy,reducing the reduction rate of cathode oxygen and protecting the second phases of aluminum alloy.The effect was comparable to that of hexavalent chromate.Ce3+released by cerium salt in water could form cerium oxide or hydroxide and deposit on the surface of aluminum alloy,protecting aluminum alloy from corrosion.In this paper,cerium vanadate was loaded on attapulgite(ATP)by hydrothermal method to prepare composite pigment ATP-CeVO4,which was added to epoxy coating and applied for corrosion protection of AA2024-T3,so as to realize the synergistic protection of cerium and vanadate ions.After immersion tests,EIS tests and accelerated corrosion tests,it was proved that the pigment could release corrosion inhibitor ions to form a protective layer on the metal surface when electrolyte solution invaded the coating,providing good corrosion resistance for the coating.The accelerated corrosion tests showed that the optimum amount of 0.2ATP-CeVO4 pigment in epoxy coating was 1.0 wt.%,and the optimum amount of 0.6 ATP-CeVO4 pigment was 5.0 wt.%.The adhesion tests showed that the active corrosion inhibition effect of the coating after adding ATP-CeVO4 pigment was at the cost of adhesion loss to some extent.The addition of ATP or ATP-CeVO4 pigment to the epoxy coating had little effect on the contact angle of the coating.Due to the good thermodynamic stability and impermeability for molecules,graphene oxide(GO)is an excellent material as barrier pigment for coatings.However,the tendency of agglomeration of nanomaterials has limited the application of GO in anti-rust coatings.In this study,the silane coupling agent AMS 10 was grafted onto GO to overcome the tendency of agglomeration in epoxy coating.The silane coupling agent AMS 10 and the organic inhibitor IBA were grafted onto GO surface to provide active corrosion inhibition on the basis of good barrier property.The modified GO pigment was added to the epoxy coating and applied to protecting Q235 carbon steel.After immersion tests,EIS tests,accelerated corrosion tests and the adhesion tests,the results showed that AMS 10 grafted GO could effectively promote the dispersion of GO in the coating,delay the invasion rate of electrolyte solution,make up for the loss of coating adhesion caused by the introduction of pigment,improve the corrosion resistance of coating.The addition of silane AMS 10 and organic corrosion inhibitor IB A grafted GO could make the epoxy coating release corrosion inhibitor to form a protective film on the surface of carbon steel when coating was invaded by electrolyte solution,make up for the loss of coating adhesion caused by the introduction of pigment and improve the corrosion resistance of the coating. |
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