Enhanced corrosion resistance of waterborne polyurethane containing sulfonated graphene/zinc phosphate composites

•Traditional phosphating film requires a lot of energy and reaction time.•Zinc phosphate has been widely used as a non-toxic anticorrosive filler in coatings but has shortcoming such as insufficient anti-corrosion efficiency.•We synthesize the spherical sulfonate graphene/zinc phosphate composites, and the specific morphology possess the thinner layer nanosheets，which was different form traditional zinc phosphate crystal.•The corrosion current density (icorr) and corrosion rate(μ) can be improved significantly by SG-ZP(0.5 wt%) barrier(icorr=0.4252 μA/cm2, the charged transfer resistance (Rct) was up to 10.937×103 Ω cm2), and the protection efficiency(η) value increases at least 95.9%. Compared with solvent-based resins, waterborne resins still have defects such as insufficient anti-corrosion efficiency. In this paper, the sulfonated graphene/zinc phosphate composites were prepared as an anti-corrosion filler and doped into waterborne polyurethane resin. The morphology of composites is different from pure zinc phosphate. The optimal corrosion resistance can be obtained by adding 0.5 wt% sulfonated graphene/zinc phosphate fillers characterized by Potentiodynamic polarization curves and EIS analysis The corrosion current density (icorr) was 0.4252 μA/cm2 and the charged transfer resistance (Rct) was up to 10.937 × 103 Ω cm2, which show a good potential as anti-corrosive fillers in waterborne coatings system.