Study On Construction And Properties Of PH Responsive Intelligent Self-repairing Coating

The corrosion process of metal materials is often complex,so it is of great economic significance to solve this problem effectively.Silane coating on metal surfaces is a common method,which provides a dense barrier to prevent the invasion of corrosive substances,such as electrolytes,oxygen and water,from direct contact with metal substrates.The development of intelligent self-repairing coatings with active anti-corrosion and self-healing protection potential plays an important role in maintaining the long-term performance of metal structures in corrosive chemical environment.At present,the development of advanced intelligent anticorrosive coatings for different applications has become the focus of attention.Innovative multi-functional coatings have excellent stimulus response functions.If they are properly used,a class of coatings with "active" anticorrosion functions will be produced.In this paper,a p H responsive intelligent self-repairing coating was constructed by doping intelligent nanocontainers that can respond to p H value,thus prolonging the service life of metals.The specific research results are as follows:(1)A smart silica nanocontainer loaded with 2-mercaptobenzothiazole was synthesized by layer-by-layer self-assembly and embedded in composite organosilane coating for anticorrosion of low carbon steel.The BET test results show that the mechanically stabilized silica nanoparticles have the characteristics of large specific surface area,narrow pore size distribution and large pore volume.This also provides conditions for the full loading of corrosion inhibitors.In addition,the Zeta potential and particle size tests showed that the polyelectrolyte shell was successfully prepared.The corrosion resistance of the coating was studied by electrochemical impedance spectroscopy and polarization curve.The results show that the addition of intelligent silica nanoparticles can improve the corrosion resistance of the coating.(2)the packaging of BTA in ZIF-8 was successfully realized by a simple "one-pot method",and then its surface was hydrophilically modified with tannic acid,and the intelligent nanocontainer(ZBT)obtained had high corrosion inhibitor loading rate.Release experiments show that ZBT,as a p H response release system,has potential in the preparation of self-repairing anticorrosive coatings.The LDH structure on the surface of mild steel substrate can be obtained by electrodeposition,which enhances the corrosion protection of the substrate and the adhesion between the substrate and the top coating.The composite silane coating was prepared on the surface of carbon steel with LDH layer.The anti-corrosion performance of the composite coating was evaluated by electrochemical impedance spectroscopy.The results show that ZBT can effectively improve the corrosion resistance of the coating and make the coating have excellent self-healing properties.The outstanding properties are related to the good compatibility between ZBT and the coating,the reduction of the porosity of the coating and the release of corrosion inhibitor when corrosion occurs.At the same time,tannic acid has a synergistic effect: not only improve the hydrophilicity of nanoparticles and enhance their dispersion in the coating,but also when ZBT is dissociated,tannic acid can form a corrosion inhibitor adsorption film on the metal surface,thus greatly improving the service life of the metal.