Tailoring the corrosion resistance of Zn-Mn coating by electrodeposition from deep eutectic solvents

Abstract

Well adhered, homogenous coatings were obtained from deep eutectic solvents (DES) based on choline chloride and urea, at current densities up to 20 mA cm-2. The coatings' morphology was analyzed by atomic force microscopy, determining the agglomerates size and distribution. The corrosion stability of these deposits was analyzed in 3 wt. % NaCl solution by electrochemical impedance spectroscopy and polarization measurements, and compared with coatings deposited from a conventional water-based electrolyte. The influence of deposition current density and surface morphology, as well as of DES type, on the corrosion resistance was analyzed. It was shown that electrodeposition from DES enables incorporation of greater Mn amounts, that induced a pseudo-passivation effect, which, in turn, resulted in superior corrosion resistance.