Preparation And Anti-corrosion Properties Of Two-dimensional Nanofiller/epoxy Composite Coatings

Many metals and their alloys face severe corrosion problems.The corrosion reaction of metals can cause irreversible damage to metals.Covering metal surfaces with anti-corrosion coatings is an effective and economical anti-corrosion method.In recent years,two-dimensional（2D）nanomaterials as fillers have been mixed into the coatings to construct two-dimensional nanocomposite coatings with durable corrosion resistance.The rich modification strategies of two-dimensional materials also endow the coatings with additional anti-corrosion properties.In this paper,two two-dimensional anti-corrosion nanofillers were designed by using the barrier properties of two-dimensional materials to corrosive ions to improve the anti-corrosion performance of water-based epoxy resins,and the anti-corrosion mechanism of composite coatings was explored.The main research contents of this paper are as follows:（1）Preparation and corrosion resistance of PDA-BN@CeO₂nanomaterials.In this chapter,hexagonal boron nitride（h-BN）surfaces were modified by the adhesion ability of polydopamine（PDA）to various substrates,and a novel PDA-BN@CeO₂nanomaterial was synthesized by in situ hydrothermal method.The physical and chemical properties of the as-prepared nanomaterials were studied by various characterization methods,and their dispersibility in an aqueous solution was investigated.The dispersion in the coating played a positive role;electrochemical measurements（EIS）and salt spray test results showed that the composite coating exhibited significant superiority in long-term corrosion protection after immersion in 3.5 wt%Na Cl solution for 35 days.The low-frequency impedance modulus|Z|_0.01Hzis nearly three orders of magnitude higher than that of the pure epoxy coating,and the carbon steel surface coated with the composite coating has only a small area of??pitting corrosion after 21days of exposure in a salt spray chamber.The high protective ability of the2D composite coating can be attributed to the synergistic effect of the well-dispersed BN nanosheets extending the corrosive medium diffusion path and CeO₂as a corrosion inhibitor to prevent the corrosive ions from contacting the metal substrate.This study provides a new way for the development of h-BN-based anti-corrosion materials.（2）Preparation and corrosion resistance of Ce-doped Mg Al-LDH@PANI nanomaterials.This chapter obtained Ce-doped LDH（CL）by a hydrothermal one-step synthesis method.After the CL was modified with a silane coupling agent KH560,aniline was polymerized on the CL sheet in an ice-water bath to obtain a Ce-doped Mg Al-LDH@PANI Nanomaterials（CLP）.The LDH before and after PANI modification was compared,and the effect of PANI modification on the chemical structure and microscopic morphology of nanomaterials were explored.The effect of CLP nanofillers’addition on the coating’s mechanical properties was studied,and the results showed that the CLP/EP composite coating had better coating adhesion and scratch resistance.EIS was used to evaluate the anti-corrosion performance of CLP/EP composite coatings.The results showed that Ce³⁺and PANI in CLP had a synergistic anti-corrosion effect.The addition of CLP endowed the coating with high-efficiency anti-corrosion and self-healing properties.The excellent performance of the CLP/EP composite coating is related to the good dispersion of CLP in water-based epoxy resin,prolonging the corrosion electrolyte diffusion pathway,and the passivation effect of PANI on the metal surface,and the corrosion inhibition effect of Ce³⁺.