Structure-Dependent Corrosion Behavior of Electrodeposited Zn Coating

Abstract

In the present work, zinc (Zn) coating was developed on an interstitial-free (IF) steel from Zn sulfate bath using direct current (DC) and pulse current (PC) electrodeposition techniques at different current densities of 10, 30, and 60 mA/cm(2). The x-ray diffraction (XRD) analysis of the coatings reveals that the higher atomically dense (0002) crystal plane of the pure Zn in the PC deposits is pronounced as compared to the DC deposits. The scanning electron microscopic (SEM) study displays finer and compact morphology of the PC deposits as compared to the DC deposits. The electrodeposits change from coarser to finer morphology with an increase in current density in both the electrodeposition techniques. All the PC deposits show a higher water contact angle (WCA) as compared to the DC deposits at each applied current density. The finer and compact coating morphology, higher WCA values with the dominance of a higher atomically dense (0002) crystal plane as well as the higher fraction of simonkolleite phase lead to the higher corrosion resistance of the PC deposits than the DC deposits.