| In this paper,chromium free composite passivation solution were prepared by solution blending method.Cationic silicone modified epoxy resin was used as film forming material and blended with different kinds and content of nanoparitlces or corrosion inhibitors.The corrosion resistance of passive film on the surface of hot galvanized steel sheet was studied by polarization curve,electrochemical impedance spectroscopy and neutral salt spray corrosion test.Cationic polypyrrole aqueous dispersion were synthesized by the use of cationic stabilizer.Effects of stabilizer amount and pyrrole monomer amount on the synthesis of polypyrrole dispersion were investigated.The results show that when the mass ratio of the stabilizer to pyrrole is 10: 1,the pyrrole content is 0.2 %,the stable polypyrrole dispersion can be obtained.The results of nano-particle size analyzer show that the average particle diameter is about 141.8 nm.Using cationic silicone modified epoxy resin and silane coupling agent ?-(2,3-epoxypropoxy)propytrimethoxysilane(KH560)as the main film-forming materials,orthogonal experiment was carried out by altering the amount of tannic acid and polypyrrole.The orthogonal test results show that the optimal formula of composite passivation solution is as follows: cationic silicone modified epoxy resin 12.75%,KH560 3.0 %,PPy 0.01 %,tannic acid 0.4 %.Laponite was modified by cationic stablizer.Modified Laponite/orgainc silicone modified epoxy resin composite passive film was prepared by using the orgainc silicone modified epoxy resin as the main film-forming material.Effect of the content of.Laponite on the anticorrosion performance of composite passive film was studied by electrochemical measurement.The results show that when the Laponite is 1 wt % of the film-forming material,the corrosion resistance of the composite passive film is the best.The value of corrosion current density and corrosion potential is 1.785×10-6 A·cm-2 and-1.052 V,respectively.Effects of the kind and content of corrosion inhibitor on the anticorrosion performance of composite passive film are investigated.The results show that the kind of corrosion inhibitor has effect on the passive film.When the corrosion inhibitor content is as follows: sodium molybdate 0.73%,sodium vanadate 0.18 %,ammonium fluotitanate 0.108 %,tannic acid content 0.6 %,the anticorrosion performance of the composite passive film is best.The addition of phytic acid lowered the corrosion resistance of the composite coating.Graphene/cationic silicone modified acrylic emulsion composite coating were prepared with different graphene content by using cationic silicone modified acrylic emulsion as film-forming substance.Electrochemical measurement results show that the addition of graphene has a certain effect on the anticorrosion performance of composite coating.With the increase of graphene content,the anti-corrosion performance of the coating gradually increased.When the graphene content is 0.15 %,the anticorrosion performance of the coating is the best. |
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