| Metal materials have been widely used in various fields because of their excellent properties,but the corrosion of metals has caused great losses to the economy.In order to reduce the loss caused by metal corrosion,people have developed many metal anti-corrosion methods,such as surface modification,anti-corrosion alloy,coating protection,electrochemical protection and so on.Among them,anticorrosion coating is widely used in metal corrosion protection because of its advantages of high cost performance and strong application.The properties of coatings largely depend on the properties of resin matrix itself.Epoxy resin is one of the most commonly used base resins in coatings because of its good adhesion and excellent chemical corrosion resistance.Moreover,epoxy resin and curing agent need to be used in a complete set to produce cross-linking reaction to form mesh macromolecules,so curing agent plays a vital role in epoxy resin coating system.However,the poor temperature resistance and chemical resistance of common epoxy resin coatings greatly limit its application and promotion.In recent years,various epoxy resins and curing agents have been widely used in the development of coatings.Therefore,it is of great significance to choose the appropriate epoxy resin and curing agent to prepare the anti-corrosion coating with excellent comprehensive performance and enhance the anti-corrosion performance through further modification.In this paper,three kinds of epoxy resins(phenolic epoxy resin,amino epoxy resin,bisphenol S type epoxy resin)and two kinds of curing agents(aromatic amine4,4' –diaminodiphenyl sulfone and 4,4'-bis(4-aminophenoxy)diphenyl sulfone)were selected,and six kinds of coatings were prepared by cross-testing.The results showed that phenolic epoxy resin with 4,4'-double(4-aminophenoxy)diphenyl sulfone curing to form coating system(FO)has the most excellent anti-corrosion performance.The reason is that the crosslinking density of the phenolic epoxy resin is higher,and 4,4'-bis(4-aminophenoxy)diphenyl sulfone has better curing agent chain flexibility,synergy leads to less coating defects.The penetration ability of blocking corrosive medium is stronger,and the anticorrosion performance is improved.In order to enhance the corrosion resistance of the coating,polyethersulfone resin with strong corrosion resistance was introduced into the above preferred coating system(FO)as the modified resin,and a series of composite coatings(FP)with different polyethersulfone addition ratios were prepared.Through the performance test of EP coatings,the results show that the long-term corrosion resistance of the coatings increases first and then decreases with the increase of the ratio of polyethersulfone resin.The best corrosion resistance of the coatings is when the ratio of epoxy resin to polyethersulfone resin is 100:25(FP-25).This is because the polyethersulfone has better anticorrosion performance.After adding the polyethersulfone,the internal structure of the coating changes from dough structure to sheet structure.The synergistic effect leads to the enhancement of the barrier ability of the coating to the corrosive medium and the improvement of the anticorrosion performance.In order to further enhance the corrosion resistance of the coating,a series of composite coatings(HFP)with different contents of mica ferric oxide(MIO)were prepared by introducing the scaly mica ferric oxide(MIO)as the modified filler into the optimal coating system(FP-25).Through the performance test of HFP coatings,the research results show that the corrosion resistance of the coating increases first and then decreases with the increase of MIO content.When the addition amount is 5%(HFP-5),the corrosion resistance of the coating is the best.The reason is that the scaly mica ferric oxide(MIO)can extend the diffusion channel of corrosive media and be blocked by the overlap of MIO particles,so that the penetration and shielding effect of corrosive media are enhanced and the corrosion resistance of the coating is better. |
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