Synthesis and characterization of a new generation of inhibitive pigment based on zinc acetate/benzotriazole: Solution phase and coating phase studies

• A hybrid inhibitive pigment based on zinc acetate/benzotriazole was synthesized.
• The chemical composition and morphology of the pigment was investigated.
• Zinc acetate/benzotriazole pigment showed good inhibitive properties.
• Zinc acetate/benzotriazole enhanced the corrosion resistance of the epoxy coating.

An organic/inorganic hybrid corrosion inhibitive pigment based on zinc acetate/benzotriazole was synthesized. The chemical composition of the pigment was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. In addition, the morphology of the pigment was studied by scanning electron microscopy. The pigment solubility in 3.5 wt.% NaCl solution was characterized by UV–Visible, total carbon content and inductively coupled plasma-optical emission spectrometer analyses. The corrosion inhibition properties of the zinc acetate/benzotriazole was compared with conventional zinc phosphate pigment in 3.5 wt.% NaCl solution containing pigments extracts on mild steel samples by polarization test and electrochemical impedance spectroscopy. X-ray photoelectron spectroscopy and scanning electron microscopy characterizations were performed on the steel samples exposed to the extracts to investigate the surface chemistry and morphology of the pigment, respectively. Also, the effects of addition of zinc acetate/benzotriazole and zinc phosphate pigments on the corrosion protection performance of the epoxy coating were studied. Results obtained from X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses confirmed that a complex of Zn-benzotriazole was successfully synthesized. The zinc acetate/benzotriazole pigment showed good solubility in NaCl solution and released inhibitive species including benzotriazole and Zn2+ cations. Zinc acetate/benzotriazole pigment showed good inhibitive properties and reduced dissolution rate of steel through forming Fe-benzotriazole and Zn-benzotriazole complexes, and Zn(OH)2 on the cathodic sites. Also, zinc acetate/benzotriazole enhanced the corrosion protection performance of the epoxy coating and reduced cathodic delamination rate of the coating more than zinc phosphate pigment.

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