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Kirilova, I.; Ivanov, Ivan B.; Rashkov, St.

doi:10.1023/a:1018425129532

Cited by 31 publications

(17 citation statements)

References 12 publications

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“…A small shift in the applied potential to more negative values caused a rapid increase in the current density and the alloy curve cross both cobalt and zinc curves. This result may indicate that, at the conditions of these experiments, the content of the metal in the coating and the kind of deposition process (normal or anomalous), would depend on the applied potential or current density, which is in agreement with the results of Roventi et al 11 and Kirilova et al 12 .…”

Section: Cathodic Linear Voltametric Curvessupporting

confidence: 90%

“…underpotential codeposition (UPD), kinetic behavior, the hydroxide suppression mechanism, and the influence of Co (III) 10 . However, it is always considered that certain experimental conditions, such as high values of current density (I), for example, can change the process from anomalous to normal and under these conditions the ZnCo alloy coatings presented a cobalt content higher than that of zinc 11,12 .…”

Section: Introductionmentioning

confidence: 99%

“…Kirilova et al 12 have observed that coatings containing small cobalt content could still be considered as sacrifice coatings, while those with high amount of this metal were nobler than steel, acting as anticorrosive barrier. In addition, Lichušina et al 10 have showed that Co-rich ZnCo coatings (15-18 % m/m Co) presented good appearance and high corrosion resistance in NaCl solution.…”

Section: Introductionmentioning

confidence: 99%

“…In most of the works, the anticorrosive performance of the alloy decreased with the elevation in % m/m Co 8,14 . Generally, to fulfill the coatings requests for a better performance, the metallic-alloy deposition baths are always developed and/or modified to enhance the cathodic current efficiency, the amount of certain metal in the coating, or even to refine the grain sizes and the decorative characteristics of the coatings 8,12 . For this purpose, a complexant agent or a leveling additive can be added to an electrodeposition bath, causing several changes on the reduction mechanism of the ions in the solution and/or in the activation energy of the electrode surface [15][16][17] .…”

Section: Introductionmentioning

confidence: 99%

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Electrodeposition of Cobalt Rich Zn-Co alloy Coatings from Citrate Bath

2014

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Section: Cathodic Linear Voltametric Curvessupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrodeposition of Cobalt Rich Zn-Co alloy Coatings from Citrate Bath

2014

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“…[1][2][3][4][5][6] Zn-Ni alloys possess better corrosion resistance compared to zinc and have been studied extensively for automotive applications. The codeposition of Zn-Ni is anomalous and a higher percent of Zn is present in the final deposit.…”

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confidence: 99%

A Novel Electrodeposition Process for Plating Zn-Ni-Cd Alloys

Kim

Popov

Chen

2003

J. Electrochem. Soc.

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Zn-Ni-Cd alloy was electrodeposited from an alkaline electrolytic bath under potentiostatic conditions. Bath analyses using a pH concentration diagram reveal that addition of a complexing agent is essential to maintain the bath stability. Introduction of a low concentration of CdSO 4 reduces the anomalous nature of the Zn-Ni deposit. Deposits obtained from the electrolytic bath which contains 60 g/L of ZnSO 4 •7H 2 O, 40 g/L of NiSO 4 •6H 2 O, 1 g/L of CdSO 4 , and 80 g/L of (NH 4 ) 2 SO 4 in the presence of additives and ammonium hydroxide at pH 9.3 has a composition of 50 wt % of Zn, 28 wt % of Ni, and 22 wt % of Cd. By optimizing the Cd concentration in the bath, it is possible to control the amount of Ni in the deposit. At large overpotentials, the surface of the electrode is covered with hydrogen which lowers the deposition current density. Rotating disk electrode studies indicated that the deposition of Cd is under mass control, while Ni deposition is under kinetic control.

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Electrodeposition of Zinc and Zinc Alloys

Winand¹

2010

Modern Electroplating

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Zinc has a standard reversible potential [À0.76 V/standard hydrogen electrode (SHE)] that is more negative than that of iron (Fe/Fe 2 þ -0.44V/SHE). For this reason zinc is used for sacrificial cathodic protection of steel against corrosion.According to Fischer [1], in metal electrodeposition, zinc can be considered as an intermediate metal, giving rise to medium values of overpotentials due to secondary inhibition resulting from adsorbed hydrolized species.In acid sulfate solutions without an organic additive, BR metallographic cross-sectional structures are obtained (BR: basis reproduction; coherent deposits with coarse crystals whose diameter increases with the deposit thickness; see Fig. 10.1). In chloride electrolytes, even coarser grains are observed, because of the more activating character of chloride ions against sulfate ions [2] and despite the complex formation in solution [3, p. 464]. In cyanide baths, on the other hand, much finer grains are obtained, and the deposits pertain to the FT (field-oriented texture: coherent deposits, with elongated crystals perpendicular to the substrate, with almost constant diameter throughout the deposit thickness) or UD types (UD: unoriented dispersion type; coherent deposit, with small crystals showing three-dimensional nucleation to occur all the time during electrodeposition). Figure 10.2 shows a deposit obtained in a cyanide solution without an organic additive: the structure is initially FT, but it becomes progressively bad. Going from a cyanide bath to a noncyanide alkaline bath should result in still worse deposits because electrolyte complexation decreases [3] and exchange current density increases [4, pp. 528-543].Accordingly, when rather thick deposits are needed and/or if a bright surface is required, organic additives are always present at high concentration (1 g L À1 or more). This always occurs in barrel-and-rack plating of small pieces of equipment, because the local current densities will vary over a wide range. For continuous plating on steel sheets or wires, constant current density and rather good hydrodynamic control may be achieved over the whole cathodic surface, and organic additives are not so much in use.Whatever the pH, zinc is always more negative than hydrogen [5]. In electrolytes where zinc is complexed, its standard reversible potential is still more negative; for instance, for cyanide baths, the reversible potential for reactionin alkaline solution is À1.26 V/SHE [6]. Consequently hydrogen evolution occurs at the cathode as a competitor to zinc deposition, resulting in a decrease of current efficiency and eventually in some atomic hydrogen diffusion into the substrate.Finally, in industrial processes electrolytic plating is an alternative to hot-dip galvanizing. Both processes have advantages and disadvantages. Continual technological improvements make it difficult to conclude in favor of one process over the other. However, hot dip always includes some surface alloying by diffusion, and the deposit thickness is less easily controlled th...

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Cited by 31 publications

References 12 publications

Electrodeposition of Cobalt Rich Zn-Co alloy Coatings from Citrate Bath

Electrodeposition of Cobalt Rich Zn-Co alloy Coatings from Citrate Bath

A Novel Electrodeposition Process for Plating Zn-Ni-Cd Alloys

Electrodeposition of Zinc and Zinc Alloys

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