Synergetic effects of pulse constraints and additives in electrodeposition of nanocrystalline zinc: Corrosion, structural and textural characterization

Pulse electrodeposition was to produce nanocrystalline (nc) zinc from alkaline non-cyanide electrolyte with primary and secondary additives. The combined effect of pulse parameters (ON-time (TON), OFF-time (T OFF), pulse peak current density (IP)) and additives on the corrosion properties (evaluated using electrochemical techniques) of zinc electrodeposits are elucidated in terms of surface morphology (using scanning electron microscope), topography and root mean square (RMS) roughness (using atomic force microscope), crystallite size, its orientations and relative texture co-efficient (RTC, %) were evaluated using X-ray diffraction. The corrosion resistance of zinc electrodeposits obtained at constant TON and IP enhanced (i.e., low Icorr and high Rct values) with increased TOFF. At constant TOFF and I P, the Icorr values increased and Rct values decreased with TON while the former decreases and latter increases with IP at constant TON and TOFF. The inclusion of primary and secondary additives into the electrolyte produced nc zinc electrodeposits at 5 Adm-2, showed enhanced protective properties (Icorr - 16 μA cm-2 and Rct - 481.8 Ω cm-2). Fine grained due to high negative overpotential, reduced roughness and higher percentage of basal plane [0 0. 2] orientation have major impact for the enhanced corrosion resistances. © 2010 Elsevier B.V. All rights reserved.