Effect of Additives on Electrodeposition of Nanocrystalline Zinc from Acidic Sulfate Solutions

Li, Moucheng; Luo, Suzhen; Qian, Yuhai; Zhang, Wenqi; Jiang, Lili; Shen, Jianian

doi:10.1149/1.2772093

Cited by 64 publications

(44 citation statements)

References 37 publications

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“…Among the large number of papers, some are of special interest because they illustrate general trends: pulse plating is studied in order to generate nanocrystalline zinc deposits [260][261][262][263]; organic additives are studied in order to control the morphology and the properties of the deposits, eventually in combination with pulse plating [264][265][266][267][268][269][270][271][272][273][274][275]; texture and surface morphology of zinc and zinc alloys deposited on low carbon steel substrate were further investigated [276][277][278]. [196].…”

Section: Recent Research Advancesmentioning

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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Section: Recent Research Advancesmentioning

confidence: 99%

Electrodeposition of Zinc and Zinc Alloys

Winand¹

2010

Modern Electroplating

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“…Acid bath was used more often, owing to its high deposition rate and cathodic efficiency. Moreover, this bath does not require complexing agents, leading to less expensive deposition process than alkaline plating bath (Li et al 2007). Organic additives were often added to alloy plating bath, which improves the properties of deposits.…”

Section: Introductionmentioning

confidence: 99%

Effect of ethyl vanillin on ZnNi alloy electrodeposition and its properties

Nayana

Venkatesha

2014

Bull Mater Sci

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The bright ZnNi alloy coating on steel surface was prepared by elctrodepostion technique using brightener ethyl vanillin (EV). To know the influence of brightener on deposition and dissolution behaviour of ZnNi alloy, cyclic voltammetric studies were carried out. FT-IR spectroscopic evidence was given to confirm selective adsorption of brightener on steel surface. The brightener enhances current efficiency and throwing power of plating bath during coating. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses in presence of brightener confirmed the change in surface morphology, phase composition and preferred orientation of ZnNi coating. In presence of brightener, nickel content of the coating was reduced at higher current density and thickness. In addition, deposit properties like appearances, hardness, adherence, ductility and corrosion resistance of ZnNi alloy deposits were also improved in bright deposit. Simultaneously, effect of deposition current density and thickness on corrosion behaviour of coating was examined.

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“…The surfactants like CTAB (cetyltrimethylammonium bromide), SDS (sodium dodecylsulfate), polyethylene glycol (PEG) and Triton X-100 were used as levelers for zinc electroplating [16][17][18][19][20]. Surfactant refines the grain size of deposit, microscopically smoothens the deposit surface, improves throwing power and solubility of brighteners in bath solution [9,21]. Some additives simultaneously act as levelers and brighteners.…”

Section: Introductionmentioning

confidence: 99%