Corrosion Inhibition of Galvanized Steel by Cobalt(II) Nitrate

Abstract

This study presents the inhibitive property of Co(II) ions in the corrosion protection of commercial hot-dip galvanized steel in aggressive solution. The polarization measurements reveal the action of Co(II) cations in the anodic branch with the inhibitive efficiency determined at 96% for 0.01 M of Co(II). The corrosion resistance was reinforced by a passive layer formed at Zn surface, that was assessed by the electrochemical measurements. The existence and the crystal structure of this protective layer was analyzed by field-emission scanning electron microscopy observations. X-ray diffraction analysis was confirmed the formation of zinc cobalt hydroxide and cobalt zinc oxide on the Zn surface that attributed to the inhibitive action of the Co cations.