Screening the anti-corrosion effect of a hybrid pigment based on zinc acetyl acetonate on the corrosion protection performance of an epoxy-ester polymeric coating

Abstract

In this study an epoxy-ester coating was filled with zinc acetyl acetonate (ZnAA). The active corrosion inhibition properties of the ZnAA pigment were studied by electrochemical noise (EN), electrochemical impedance spectroscopy (EIS) and polarization techniques. Also, the surface morphology and composition of the steel panels were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The electrochemical measurements revealed the effective corrosion inhibition properties of the ZnAA pigment in the solution phase. Polarization test results revealed that in the presence of ZnAA both cathodic and anodic current densities decreased. In fact, the Zn2+ cations and acetyl acetonate anions formed inhibitive films based on Fe2+-acetyl acetonate and zinc oxide/hydroxide complexes on the anodic and cathodic regions. Results of theoretical ab initio quantum mechanics and molecular dynamics simulations evidenced that the inhibitors strongly adsorbed to iron surface through donor–acceptor interactions. The EIS results showed that the epoxy-ester coating protection performance was significantly enhanced by addition of ZnAA hybrid pigment. The ZnAA pigment enhanced the barrier performance of the coating and provided active inhibition properties.