Enhancing corrosion resistance of nickel surface by electropolishing in a deep eutectic solvent

Abstract The electropolishing of Ni surface was performed using a deep eutectic solvent (ethaline) belonging to a new generation of ionic liquids. The experiments conducted at three different values of electrode potential of anodic treatment (1.5, 1.8 and 2.0 V vs. Ag pseudo-reference electrode) showed that an increase in electrode potential results in an appreciable improvement in surface morphology (surface leveling and smoothing) and a decrease in surface roughness coefficients. The corrosion resistance of electropolished Ni in 3% NaCl solution was estimated by means of electrochemical impedance spectroscopy. An increase in the electrode potential of electropolishing causes an improvement in corrosion resistance of Ni surface, which may be due to selective dissolution of surface defects and the reduction of both real surface area and the degree of electrode heterogeneity.