| Epoxy paint has been the most widely used anti-corrosion coating for a long time. However, with the increase of industrialization, the environment becomes deteriorating, which needs to reseach coatings with higher anti-corrosion property. Adding flaky sericite to epoxy coating was emproved to be an effective way, on the one hand, it can retard the proliferation of small molecules, such as water and oxygen; on the other hand, it can effectively retard chemical erosion and play good protection. But, as is known to all, sericite is an inorganic silicate mineral with hydrophilic propertity, it has many shortcomings, such as, it is difficult to be moist or to disperse in organic paint and easy to reunion and so on. So, in this paper, many ways of surface modification of sericite were studied, and further the influence of modified sericite on the anti-corrosion propertity of coatings were studied.In this paper, three kinds of modification methods of sericite were studied, they are coupling agent grafted, organic - inorganic composite coating and the two kinds of coupling co-grafting. The physical and chemical properties of modified sericite were characterized by scanning electron microscopy (SEM), energy dispersive spectrum (EDS) analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and contact angle test, it turned out that the surface properties of sericite were improved. And the effects of modified seticite on anti-corrosion properties of coatings were studied by electrochemical impedance spectrum (EIS) technology. The key findings are as follows:1) After modified with KH-550,KH-560 and KH-570, the superficial appearance, the stem grafting effect, lipophilic and other perperties of sericite were tested using SEM, FT-IR, angle of contact and electron microscope, it shows that three kinds of coupling agents were grafted on the surface of sericite, considering their effects, KH-550 is the best, KH-570 is followed, KH-560 is more poor, and the best dosage of modifier is 6wt%.2) It was studied that after modification a uniform layer of Cr2O3 was coated on the surface of sericite using XRD. EDS results show that when the amount of chromium nitrate is 60wt% of sericite, the modification effect is the best. Contact angle tests show that when coated with KH-550 and Cr2O3, the hydrophobicity of sericite is better than that single coated with Cr2O3.3) Sericite were composite modified with two kinds of coupling agent KH-550 and KH-570. FT-IR, SEM and contact angle results shows that after modification sericite was successfully grafted by coupling agent, and the hydrophobicity after modification has been greatly improved, the best use ratio of KH-550/KH-570 is 5 to 1. By orthogonal experiment the optimum condition is at 70℃, with PH is 9, modified for 2h.4) The polarization curves test result shows that coating with KH-550/Cr2O3/sericite compared with coating with KH-550/sericite, the corrosion potential was significantly improved, and the corrosion current is greatly reduced, it indicated that the coating reduced the corrosion rate, it has good protection propertity.5) The anti-corrosion properties of the coatings were measured by EIS technology. The results showed that, resistance of the coating with modified sericite is more than 108?, that is 10 times of coating with sericite, and is 103-4 times higher than that of varnish. Comparing impedance of different coatings, it can be found that, coating with two kinds of coupling modified sericite has the highest impedance (6.6×108?), coating with organic - inorganic composite modified sericite followed(3.25×108?), and coating with single coupling modified sericite is smaller(1.75×108?).
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