Faculty of Technology, University of East Sarajevo, Lukavica, Bosnia and Herzegovina
The topic of this paper is testing corrosion stability of electrodeposited Zn-Mn coatings by using electrochemical impedance spectroscopy (SEI). The coatings were deposited galvanostatically on a 3x3 cm steel. 99.99% pure zinc was used as the anode. The electrodeposition was carried out from four chloride solutions. Solution 1 was without manganese (3mol/dm3 KCl, 0,42mol/dm3 H3BO3, 0,45mol/dm3 ZnCl ), solutions 2-4 had the same concentration of KCl, H3BO3 and ZnCl2 as in solution 1 and only MnCl2·4H2O was added in various concentrations. Final concentrations of solutions 2-4 were as follows: solution 2 - [Mn2+]:[Zn2+]=1:1 (0,45mol/dm3 MnCl2·4H2O); solution 3-[Mn2+]:[Zn2+]=1:2 (0,225mol/dm3 MnCl2·4H2O,); solution 4-[Mn2+]:[Zn2+]=2:1 (0,9mol/dm3 MnCl2·4H2O). Zn-Mn coatings were electrodeposited on chemically prepared samples of steel (cathodes) for 15 minutes from all solutions at current densities of 1 А/dm2 , 2 А/dm2 and 4 А/dm2 . The obtained results showed that the Zn-Mn coatings deposited at all current densities have a higher corrosion stability compared to the pure zinc coating. For examle, of all the coatings deposited at the current density of 1A/dm2 the coating deposited from solution 2 had the greatest corrosion stability, whereas the coatings from solutions 3 and 4 were more corrosion resistant at the current density of 2 and 4A/dm2 . Corrosion resistances, determined from the Nyquist diagrams (Zimag) of the pure Zn coatings, were in the range of 80-130 Ω, depending on the deposition current density, while the resistances of the alloy coatings were around 150-200 Ω. Based on results obtained by electrochemical impedance spectroscopy it can be concluded that the most resistant Zn-Mn coatings were deposited from the solution 3 ([Mn2+]:[Zn2+]=1:2), at the current densities of 2 A/dm2 and 4 A/dm2 .
The statements, opinions and data contained in the journal are solely those of the individual authors and contributors and not of the publisher and the editor(s). We stay neutral with regard to jurisdictional claims in published maps and institutional affiliations.