A Model for Nanolaminated Growth Patterns in Zn and Zn‐Co Electrodeposits

Yan, Haibo; Downes, J; Boden, P. J.; Harris, S.J.

doi:10.1149/1.1836682

Cited by 100 publications

(45 citation statements)

References 3 publications

(4 reference statements)

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“…During electroreduction, the localized concentration of hydroxide ions in close proximity to the cathode surface will increase and result in the formation of MeOH ads . The probable chemical reaction path of zinc ions reduction is specified below [18].…”

Section: Polarization Studiesmentioning

confidence: 99%

Studies on electrodeposition of Zn–MoS2 nanocomposite coatings on mild steel and its properties

Vathsala

Venkatesha

2011

J Solid State Electrochem

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Pure zinc and Zn-MoS 2 composite coatings were prepared by electrodeposition from zinc sulfate-chloride bath containing uniformly dispersed MoS 2 nanoparticles. The effect of MoS 2 on the deposition properties morphology, crystallographic orientation, and corrosion behavior were studied. The electrokinetic properties (zeta potential) and size distribution statistics in plating bath for the particles were evaluated using dynamic light scattering experiments. The Zn and Zn-MoS 2 deposition process was studied by linear polarization and cyclic voltammetry. Scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction analysis, and potentiodynamic polarization measurements were used to characterize the coatings. The addition of MoS 2 to the electrolyte significantly changed the microstructure and crystallographic orientation of the zinc deposits and enhanced the corrosion resistance of the coatings. The morphological and electrochemical properties of the zinc coatings were observed to be significantly affected by the incorporation of MoS 2 particles into the zinc matrix.

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Section: Polarization Studiesmentioning

confidence: 99%

Studies on electrodeposition of Zn–MoS2 nanocomposite coatings on mild steel and its properties

Vathsala

Venkatesha

2011

J Solid State Electrochem

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“…Interestingly, the multilayers of zinc are obtained both by pulse plating [77] and by selfoscillations of current at constant cathode potential [78]. Ultrasonic agitation was considered to smooth the surface [79,80].…”

Section: Some Further Considerations Concerning Zinc Barrel-and-rack mentioning

confidence: 99%

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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“…This fact can suggests an insignificant inhibition of the zinc reduction at −1.040 V vs. SCE, displacing it at −1.054 V vs. SCE. Such results are usually interpreted as the adsorption of the substrate on the electrode surface and blockage of its active sites [27,28]. An increase in the value of current density is connected with the additivity of the currents.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reactions of Sodium 2-Ethylhexyl Sulfate Salt

2017

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The electrochemical reactions of sodium 2-ethylhexyl sulfate (EHS) and its effect on the Zn 2+ electroreduction have been investigated at a mercury electrode using cyclic voltammetry. It has been shown that the reduction takes place in two steps. The presence of EHS in the solution containing Zn 2+ ions moves slightly the potential of zinc reduction towards more negative potentials and causes a slight increase in current density. The differential capacity-potential and differential capacity-time measurements indicate strong adsorption in a wide potential range on the electrode surface. In the potential range −0.46 to −0.86 V vs. saturated calomel electrode and at the concentration lower than the critical micelle concentration (CMC), adsorption for the longer time is hardly reversible. At the concentration higher than the CMC, the formation of hemispherical surface micelles is observed. The theoretical maximum degree of electrode coverage computed with the use of quantum-chemical calculations is equal to 3.53 × 10 14 particles cm, and it is larger than the value determined experimentally from cyclic voltammograms. In the case of electrochemical reaction, at a current of 0.3 A, during 180 min, the obtained mineralization of EHS is only 3%.

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A Model for Nanolaminated Growth Patterns in Zn and Zn‐Co Electrodeposits

Cited by 100 publications

References 3 publications

Studies on electrodeposition of Zn–MoS2 nanocomposite coatings on mild steel and its properties

Studies on electrodeposition of Zn–MoS2 nanocomposite coatings on mild steel and its properties

Electrodeposition of Zinc and Zinc Alloys

Electrochemical Reactions of Sodium 2-Ethylhexyl Sulfate Salt

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