Synergistically assembled graphene/ZnO composite to enhance anticorrosion performance of waterborne epoxy coatings

In this work, waterborne epoxy resin and graphene/ZnO (Gr/ZnO) were employed as the matrix and nanofiller to construct composite coatings with enhanced anticorrosive performance. The corrosion protection properties of the coatings were significantly improved by the dispersed Gr sheets, as well as the parallelly assembled ZnO nanoparticles. The most remarkable improvement was achieved by adding 0.04 wt% of Gr and 0.4 wt% of ZnO in the Waterborne Epoxy (WEP) coatings, where the highest impedance was 200 530 Ω cm² on Gr_0.04–ZnO_0.4, far more than pure epoxy with 6186 Ω cm² after 7 days of immersion in electrolytes. Furthermore, the Gr_0.04–ZnO_0.4 coatings and corresponding corrosion products immersed in a 3.5% NaCl solution for 30 days were also characterized, which could further reveal anticorrosion mechanisms of the graphene modified WEP coatings and the passivated effect of ZnO. Through the mechanism analysis, we also found that ZnO could be employed as the barrier reinforcement to improve the dispersibility of graphene in WEP coatings, and the parallel assembly of graphene occurs spontaneously, leading to remarkable improvement of anticorrosion properties.

This is the first example of synergistically assembled Gr/ZnO sheets to improve the corrosion protection properties of WEP coatings, and Gr_0.04–ZnO_0.4 exhibited the highest impedance of 200 530 Ω cm² compared to pure WEP of 6186 Ω cm².