Electrochemical Obtaining and Corrosion Behavior of Zinc-Polyaniline (Zn-PANI) Hybrid Coatings

Abstract

Hybrid zinc-based coatings with embedded polyaniline (PANI) particles in the metal matrix are obtained in a one-step process via electrodeposition on low-carbon steel plates. The aim is directly to use the inhibitor properties of polyaniline for improved protection against corrosion in chloride containing medium (5% NaCl solution). PANI-particles (concentration of 0.025 g/L) are added to the starting zinc electrolyte in dispersed form—the latter being obtained via oxidation polymerization in the presence of stabilizers (polyvinyl pyrrolidone (PVP) or colloidal SiO2). Electrodeposition conditions are equal to those for obtaining an ordinary zinc coating. The surface morphology of the hybrid coatings before and after corrosion treatment in the model medium is characterized with SEM. The influence of the incorporated PANI/PVP- or PANI/SiO2-particles on the protective properties of the coatings is evaluated by the application of electrochemical (potentiodynamic polarization, open-circuit potential, polarization resistance, cyclic voltammetry) as well as X-ray based (X-ray diffraction and X-ray photoelectron spectroscopy) methods. A discussion and some conclusions about the reasons for the improved corrosion resistance and protective ability of the hybrid coatings in that model medium are proposed.