通过物理混合将自制的石墨烯分散液与双组分水性环氧树脂制备成石墨烯环氧树脂。用扫描电镜(SEM)考察了石墨烯在水溶液中的分散情况。通过极化曲线、交流阻抗谱和中性盐雾试验探讨了含0.5%石墨烯的E44水性环氧涂层(0.5%G-E44)在模拟海水溶液中的隔水和耐腐蚀性能并与纯环氧涂层E44进行比较。结果表明:石墨烯在水溶液中分散良好,其在水性环氧树脂中层层叠加,形成了致密的物理隔绝层,减缓了水分子在涂层中的扩散速率,拥有较好的隔水性能。E44和0.5%G-E44涂层在浸泡初期的Fick扩散系数分别为5.56×10^-9 cm^2/s和1.61×10^-11 cm^2/s。添加石墨烯明显提高了水性环氧树脂涂层的防护效果,自腐蚀电流密度减小,涂层电阻和电荷转移电阻增大,200 h中性盐雾试验后涂膜平整,无明显腐蚀。
A graphene-epoxy resin was prepared by physical blending home-made aqueous dispersion of graphene and two-component waterborne epoxy resin. The dispersed graphene in aqueous solution was analyzed by scanning electron microscopy. The water isolation and corrosion resistance of the waterborne epoxy coating doped with 0.5% graphene (0.5%G-E44) in simulated seawater were studied by polarization curve measurement, electrochemical impedance spectroscopy (E1S), and neutral salt spray (NSS) test, and compared with that of untreated E44 epoxy coating. The results indicated that graphene is dispersed well in the solution and presents good water-isolating performance, which is overlapped layer by layer in the waterborne epoxy resin, forming a dense physical isolation layer and thus slowing down the diffusion rate of water molecules in the coating. Fick diffusion coefficients of E44 and 0.5%G-E44 immersed in simulated seawater at early stage are 5.56×10^-9 cm^2/s and 1.61×10^-11 cm^2/s, respectively. The protection performance of waterborne epoxy coating is obviously improved by adding grapheme, as shown by the decreasing of self-corrosion current density and the increasing of coating resistance and charge transfer resistance. The coating features a level and smooth surface after 200 h NSS test without distinct corrosion.