Synergistic enhancement of epoxy coating corrosion resistance via Zn2 + /Mn2+ dual-cation induced hypercross-linking

Waterborne epoxy resin coatings are extensively utilized in the corrosion protection of metal materials, primarily due to the excellent environmental protection capabilities. However, their hydrophilicity often limits their corrosion resistance. In order to improve the corrosion resistance of waterborne epoxy resin coatings, Zn 2+ and Mn 2+ double cations were introduced into waterborne epoxy resin in this paper to prepared the P-E-Zn/Mn composite coating with the high crosslinking density. The article systematically studied the corrosion resistance of waterborne composite coatings doped with dual cations (Zn 2+ /Mn 2+ ) and single cations (Zn 2+ or Mn 2+ ), and compares the actual situations of waterborne composite coatings under two doping conditions in salt spray tests and acid corrosion experiments. DFT calculation revealed the corrosion resistance mechanism of Zn 2+ /Mn 2+ double cation doping in waterborne epoxy resin. The experimental results showed that the corrosion resistance of P-E-Zn/Mn composite coating doped with dual cations (Zn 2+ /Mn 2+ ) is superior to that of pure waterborne epoxy resin coating and single doped (Zn 2+ or Mn 2+ ) waterborne epoxy resin coating. DFT calculations demonstrated that the adsorption effect between double cations (Zn 2+ /Mn 2+ ) with PVA and waterborne epoxy resin molecules promoted the formation of O-Zn-O and O-Mn-O bonds, thereby enhancing the curing crosslinking reaction of the P-E-Zn/Mn waterborne epoxy resin coatings. The complex cross-linking structure of O-Zn-O and O-Mn-O in P-E-Zn/Mn coating enhanced corrosion resistance and also improved resistance in acidic environments.