Optimization of deposition conditions for development of high corrosion resistant Zn-Fe multilayer coatings
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2011
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Abstract
Composition modulated multilayer alloy (CMMA) coating of Zn-Fe was developed galvanostatically on mild steel through single bath technique (SBT), using thiamine hydrochloride as additive. Electrodeposits with different coating matrices were developed, using square current pulses. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion performance of the coatings. The cyclic cathode current densities (CCCDs) and number of layers were optimized, for highest corrosion resistance. Experimental results showed that CMMA Zn-Fe coating, developed at 2.0-4.0 A/dm2, having 300 layers is ?30 times higher corrosion resistant than corresponding monolithic alloy of same thickness. The corrosion resistance increased with number of layers up to a certain number of layers; and then decreased. The better corrosion resistance was attributed to the dielectric barrier at the interface, evidenced by dielectric spectroscopy. The formation of multilayer and corrosion mechanism was analyzed using scanning electron microscopy (SEM). © 2011 Elsevier B.V. All rights reserved.
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Keywords
Cathode current density, CMMA Zn-Fe coatings, Corrosion mechanisms, Corrosion performance, Corrosion study, Corrosion-resistant, Current pulse, Deposition conditions, Dielectric barrier, Mild steel, Monolithic alloys, Multi-layer-coating, Number of layers, SEM, Single bath, Thiamine hydrochloride, Carbon steel, Coatings, Corrosive effects, Dielectric devices, Dielectric spectroscopy, Electrochemical corrosion, Electrochemical impedance spectroscopy, Iron alloys, Multilayers, Optimization, Scanning electron microscopy, Zinc, Corrosion resistance
Citation
Journal of Materials Processing Technology, 2011, 211, 8, pp. 1409-1415