| Epoxy zinc-rich coating is a special coating composed of epoxy resin and zinc powder as the main raw materials,supplemented by solvent and auxiliary agent.It has excellent anticorrosion performance,high zinc powder content in the paint film,and has cathodic protection.Therefore,it is widely used in the fields of oil storage tanks,port Bridges and other steel structures.However,due to the high zinc powder content,there are more pores in the coating due to the piling of zinc particles,which leads to the diffusion of corrosive media to the interface between the coating and steel matrix,thus shortening the protection time of the coating.In addition,due to the lack of adhesive effect of epoxy resin,the flexibility of the coating with high zinc content is reduced,and the adhesion between zinc powder and steel matrix is weakened.Aiming at the above problems,this paper uses the excellent mechanical and electrical conductivity of carbon nanotubes to reduce the zinc powder content and improve their comprehensive performance.At the same time,in view of the national requirements of environmental protection,we vigorously develop waterborne coatings,but the performance of waterborne epoxy resin used in the field of steel structure is poor.Therefore,a water-based epoxy resin was developed to prepare water-based epoxy zinc-rich coatings,and functionalized carbon nanotubes were used to improve the comprehensive properties of the coatings.Curing agent and P/B are significant for the properties of coatings.In order to prepare solvent based epoxy zinc-rich coatings with high performance,the influence of curing agent and P/B on the coating performance was investigated.The mechanical properties and anti-corrosion properties of the coating were characterized by mechanical property and salt spray test.The results showed that when the curing agent dosage was 50% of the epoxy resin and the P/B was 6.0:1,the coating exhibited better mechanical properties,and the salt spray resistance could reach 1000 h.CNTs were used to enhance the solvent based epoxy zinc-rich coating based on their good electrical conductivity and chemical stability.The influence of CNT content on the coating properties was investigated,and the mechanical properties and anti-corrosion properties of the coating were also characterized.The results showed that the addition of CNTs could obviously improve the mechanical and anti-corrosion properties of the coatings.When the content of CNTs was 0.3wt%,the mechanical properties of the coating were better.Compared with the coating without CNTs,the corrosion resistance of the coating was improved by about 60%.Water-based epoxy resin was prepared by phase transformation method,and non-ionic epoxy emulsifier was prepared by using polyethylene glycol and epoxy resin as raw materials for epoxy resin emulsification.The effects of emulsifier content and emulsifying temperature on the properties of the emulsion were investigated.The effects of the content of zinc powder on the properties of water-based epoxy zinc-rich coating were also evaluated.The results showed that the performance of the synthesized emulsion was the best when the amount of emulsifier was 20% and the emulsifying temperature was 60℃.At the same time,it was determined that the mechanical properties and corrosion resistance of the system were the optimal when the zinc powder content was 70%.In order to improve the performance of waterborne epoxy zinc-rich coating based on previous research,the effect of zinc powder content on the performance of water-based epoxy zinc-rich coating was investigated by fixing the content of functionalized CNTs(0.3wt %).The results showed that when the zinc content was 70%,the performance of the coating was better.At this time,the salt spray could reach 1000 h,which was comparable to the solvent based epoxy zinc rich coating.At the same time,electrochemical test(EIS)confirmed that,the coating corrosion resistance was the best in presence of zinc powder with a content of 70%. |
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