| At present, waterborne inorganic Zinc-rich coating is one of the longestservice life of metal anti-corrosion coatings. It is widely used in theatmosphere, oceans and other heavy duty corrosion protection field for itscharacteristics of environmental protection and excellent corrosion resistantperformance. However, the coating is brittle and the mechanical propertiesshould be improved, which limits its development. In order to improve themechanical properties and keep the outstanding corrosion protection, in thispaper, the high SiO2/K2O molar ratio potassium silicate aqueous solution hasbeen modified by silicone-acrylic emulsion.Influence of reaction temperature, variety and dosage of silane couplingagent on preparation of silicone-acrylic emulsion modified high SiO2/K2Omolar ratio potassium silicate aqueous solution has been studied. Particle sizeanalysis indicates that the particle size in the silicone-acrylic emulsionmodified high SiO2/K2O molar ratio potassium silicate aqueous solutionproduced at55℃is smaller. Results show that the prepared silicone-acrylicemulsion modified high SiO2/K2O molar ratio potassium silicate aqueoussolution has a better stability and higher pencil hardness when theconsumption of methyl-trimethoxysilane is about3%.Influence of dosage of silicone-acrylic emulsion on performance of Zinc-rich coating has been studied, the result shows that the coating has the bestmechanical properties when the dosage of silicone-acrylic emulsion is about15%. Compared to the coating before modified, the mechanical properties areobviously improved.Influence of content of Zinc powder and solid content in the silicone-acrylic emulsion modified high SiO2/K2O molar ratio potassium silicateaqueous solution on performance of waterborne inorganic Zinc-rich coatinghas been discussed. Influence of SiO2/K2O molar ratio on silicone-acrylicemulsion modified potassium silicate aqueous solution and the Zinc-richcoating has been researched. In addition, the coatings have been characterizedby scanning electron microscope (SEM), the result indicates that the properSiO2/K2O molar ratio is between5.0~6.0.Electrochemical analysis of silicone-acrylic emulsion modified waterborne inorganic Zinc-rich coating has been studied by usingelectrochemical workstation. The variation trend of corrosion open circuitpotential with the change of soak time indicates that the corrosion open circuitpotential has been increased with the increasing of SiO2/K2O molar ratio. Theresult of tafel curves demonstrates that the three different SiO2/K2O molarratios of Zinc-rich coatings all have good corrosion resistance. The result ofelectrochemical impedance spectroscopy (EIS) shows that with the increasingof SiO2/K2O molar ratio of potassium silicate aqueous solution, both of theimpedance and the shielding property of the coating have been increased andthe compactness of the coating would be better, which can efficiently resistthe osmosis of corrosive medium.The coatings before corrosion and after corrosion have been analyzed byXRD, the result demonstrates that the corrosion resistance of the silicone-acrylic emulsion modified high SiO2/K2O molar ratio waterborne inorganicZinc-rich coating is outstanding, and the main corrosion product during theimmersion time is Zn5(OH)8Cl2. |
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