| Marine ships sailing in harsh environments with high salinity and oxygen are prone to be corroded by seawater and the atmosphere and thus reduce the strength of the hull.In order to extend the life of marine metal materials in the marine environment,the coating technology with easy operation,low cost and better protection of the base metal has been widely used in various countries around the world.However,most existing hull anti-corrosion coatings still use solvent-based anti-corrosion coatings.During the use of such coatings,a large number of toxic volatile organic compounds will be released,which will cause serious environmental pollution and damage people's lives and health.Therefore,water-based anti-corrosion coatings will become the focus of future development of anti-corrosion coatings,but the anti-corrosion performance and mechanical properties of water-based coatings still have certain deficiencies compared to organic coatings,which is difficult to meet the severe atmospheric corrosion and harsh marine environment.Therefore,it is particularly important to research and prepare water-based anticorrosive coatings with excellent anticorrosive properties and mechanical properties.Based on this,this paper selects LT550 as the coupling agent,using epoxy resin and water-based silicate emulsion to react with LT550 respectively to realize the modification of water-based zinc-rich coating by epoxy resin.The mechanical properties of the modified silicate coating were explored by testing its adhesion,impact toughness and pencil hardness,and compared with the mechanical properties of the purchased water-based silicate coating.Then,different epoxy-modified silicate zinc-rich coatings were prepared by controlling the film thickness and epoxy content,and through the salt spray test,immersion test and electrochemical impedance spectroscopy and other means to characterize the corrosion resistance,and explore the corrosion mechanism.The main results are as follows:(1)Successfully prepared epoxy-modified water-based silicate coating:using silane coupling agent to graft epoxy resin and water-based silicate together,and using infrared spectroscopy to characterize the change of functional groups before and after modification.(2)The effect of film thickness on the hydrophobicity and impedance of zinc-rich coatings was studied:the water contact angle of the prepared silicate zinc-rich coatings with thicknesses of 30 ?m,60 ?m,and 90 ?m,respectively,and use the electrochemical workstation to measure the impedance value of the coating at different film thicknesses;(3)The mechanical properties of the modified silicate zinc-rich coating at different times of epoxy content were studied:the adhesion,pencil hardness and impact toughness of water-based silicate zinc-rich coatings with different epoxy contents were measured separately.And compared with the unmodified silicate zinc-rich coating,the test results show that the overall performance of the modified coating has been improved.(4)Anti-corrosion performance tests were conducted on epoxy-modified silicate zinc-rich coatings with different epoxy contents:the prepared epoxy-modified silicate zinc-rich coatings with different epoxy contents were divided into two groups,one group was put in 3.5%NaCl salt solution for soaking,the other group was put in a salt spray machine with 5%NaCl concentration for salt spray test,and the corrosion condition of the test was observed regularly.(5)The silicate zinc-rich coatings in the immersion and salt spray tests were subjected to electrochemical impedance and polarization curve measurements.The test results showed that the corrosion resistance of the silicate zinc-rich coating after modification was better than that of the unmodified coating Layer,and the corrosion resistance increases with the increase of epoxy content. |
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