The Inhibitive Effect of Artificial Seawater on Magnesium Corrosion

Abstract

The corrosion behavior of pure magnesium (Mg) immersed in 3.5 wt% NaCl and artificial seawater is evaluated by immersion test, electrochemical impedance spectroscopy (EIS), polarization curve, scanning electrochemical microscopy (SECM), and corrosion morphology analysis. The results show that the corrosion rate of the pure Mg in the artificial seawater is nearly a half of that in the 3.5 wt% NaCl, and the serious localized corrosion of Mg in the NaCl is inhibited in the artificial seawater. The main constituents MgCl 2 and Na 2 SO 4 in artificial seawater are found to be inhibitive for the corrosion of Mg. The presence of Mg 2+ ions could facilitate the formation of Mg(OH) 2 film and thus to some extent retard the dissolution of Mg. The SO 4 2– ions in the artificial seawater might be absorbed competitively against Cl − on the Mg surface to retard the corrosion of Mg. The corrosive and inhibitive effects of other anions and cations on Mg dissolution in the artificial seawater were also briefly analyzed.