A high corrosion-resistant waterborne epoxy resin coating improved by addition of multi-interface structured zinc phosphate particles

In the present study, a three-dimensional multi-interface structured zinc phosphate particle with large specific surface area was prepared by regulating the zinc phosphate crystal growth process, which was applied to develop a waterborne epoxy resin coating with better corrosion resistance. The results reveal that the multi-interface structured zinc phosphate particles could well coalesce with epoxy resin. Compared with the waterborne coating doped with and without two-dimensional zinc phosphate sheets, the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating has highest corrosion potential, lowest corrosion current density and the highest low-frequency impedance, which indicates the obvious benefits of multi-interface structured zinc phosphate particles on corrosion resistance. Moreover, the electrochemical properties tests on the waterborne epoxy resin coatings immersed in salt solution for 3000 h demonstrate that the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating almost has no changes but the other waterborne epoxy resin coatings decrease obviously. The surface characterization on the corroded waterborne epoxy resin coatings reveal that the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating possesses the relative integrated surface, while the inner corrosion has occurred in other coatings. The waterborne epoxy resin coatings with different additives sprayed on Al alloy surface could obtain the adhesion strength between 6.21 and 6.81 MPa, and the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating possesses the maximum value. Even after the salt solution immersion for 3000 hours, the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating still remains the adhesion strength above 6.21 MPa. Such excellent corrosion resistance should be ascribed to the cooperation of strengthened physical inhibition effect, decreased polar channel and complexation reaction by multi-interface structured zinc phosphate particles.