Improvement of corrosion resistance of waterborne potassium silicate zinc-rich coating by addition of Nano-ZnO/graphene

Nano-ZnO/graphene composite was prepared and added to potassium silicate zinc-rich coating in order to obtain modified potassium silicate zinc-rich anti-corrosion coating (ZG/zinc-rich coating), which would be used for the protection of the surface of the steel substrate. Its morphology and corrosion resistance were characterized by scanning electron microscopy, electrochemical testing, and salt spray testing. Compared to neat water-based potassium silicate zinc-rich coatings with 50 wt% zinc, ZG/zinc-rich coating with 30 wt% zinc and 1 wt% Nano-ZnO/graphene had better corrosion resistance because it can fill the gaps between zinc powder particles to make the coating denser and the electron transfer easier. Its adhesion, hardness, water resistance, and E_corr were all improved. i_corr was reduced by one order of magnitude. |Z|_0.01Hz was increased by six times. R_ct was increased by three times. This study indicated that Nano-ZnO/graphene not only enhances anti-corrosion performance of waterborne zinc-rich coating, but also improved the utilization rate of zinc powder.