Zinc-nickel alloys, electrodeposition

Baker, R. G., and Holden, C. A. (1985). Zinc-nickel alloy electrodeposits Rack plating. Plat. Surf. Finish., March, pp. 54-57. 

Hall, D. E. Electrodeposited Zinc-Nickel Alloy Coatings —A Review , Plating and Surface Fin., 59-65 (Nov. 1983)... 

D.E. HaU, Electrodeposited zinc-nickel alloy coatings a review. Plat. Surf. Finish. 70 (1983) 59-65. 

Rodriguez-Torres I, Valentin G, Lapicque E (1999) Electrodeposition of zinc-nickel alloys from ammonia-containing baths. J Appl Electrochem 29 1035-1044. doi 10.1023/A 1003610617785... 

In view of the high cost, when tarnish resistance of the surface is the only requirement it is customary to use the thinnest possible coatings of rhodium (0-000 25-0-000 5 mm). Since rhodium deposits in this thickness range, like thin electrodeposits of other metals, show significant porosity, readily corrodible metals, e.g. steel, zinc-base alloys, etc. must be provided with an undercoating deposit, usually of silver or nickel, which is sufficiently thick to provide a fairly high level of protection to the basis metal even before the final precious metal deposit is applied, and, in this way, to prevent accelerated electrochemical corrosion at pores in the rhodium deposit. 

Rodriguez-Torres etal. [235] have used ammonia-containing baths for Zn-Ni alloy electrodeposition on Pt. Zinc and nickel species exist in the form of [Zn(NH3)4] + and [Ni(NH3)6] " complexes in such solutions. The deposition at pH 10 was investigated and compared with deposition from ammonium chloride baths at pH 5. The Ni content in the alloys was found to be 40-60% higher from the ammonia-containing bath than from the acidic baths. The deposition mechanism was found to be affected by complexation of the metal cations by ammonia. 

Sectrodeposition of nickel and cobalt has been investigated intensively in aqueous solutions. Both metals are interesting for nanotechnology as magnetic nanostructures can be formed in aqueous solutions [47]. Hovrever, the bulk electrodeposition is accompanied by a massive hydrogen evolution. Both elements can also be deposited from acidic chloroaluminate liquids [48,49]. Cobalt and zinc-cobalt alloys... 

This is of course not the case when working with room temperature ionic liquid systems. Electrochemical and spectroscopic studies of cobalt, copper, and nickel, have been carried out in the AlClj-butylpyridinium chloride molten salt system. The direct current and pulsed current electrodeposition of Ni-Al alloys has also been shown in acidic AlCls-butylpyridinium chloride ionic liquids. This particular alloy has also been shown to be successful in AlCl3-[C2-mim]Cl ashave Co-Al andCu-Al. Electrochemical techniques can also be used to calculate the diffusion coefficients of metal ions. Table 21.2.6 shows the calculated diffusion coefficients and stokes-Einstein products of cobalt(II), copper(I), nickel(II) and zinc(II) in the 40-60 mol% [Cj-mimlCl-AlClj ionic liquid. 

The mechanism of co-deposition of boron in Ni-B coatings prepared by electrodeposition technique is not yet fiilly understood. It is assumed that boron is incorporated into Ni-B coating due to the adsorption of DMAB on the surface of already formed nickel which is then decomposed to elemental boron. Therefore, the amount of boron codeposited with nickel can be determined by the distribution of DMAB, and the thickness of the diffusion layer at the cathode surface, regardless of the electrode potential [26]. The mechanism of incorporation of zinc into electrodeposited Ni-B matrix can be explained on the basis of formation and subsequent reduction of ZuNi-t-aj species at the surface of the steel substrate. Miranda et al. have observed that the formation of Ni-rich phase in Zn-Ni alloy occurs at low potentials through the formation and subsequent reduction of ZnNi ad species. This observation tends to suggest that a similar phenomenon occurs in the electrodeposition of Ni-Zn-B which is very much similar to Ni-Zn-P coatings[27]. 

Nickel contents of up to about 15% are incorporated in a zinc coating, usually by electrodeposition but also by mechanical coating. (The addition of 0.06-0.11% nickel in hot dip galvanizing, to suppress excessive Zn alloy formation, does not influence the corrosion resistance Van Eijnsbergen unpublished report). 

Many alloys may be electrodeposited, including copper-zinc, copper-tin, lead-tin, cobalt-tin, nickel-cobalt, nickel-iron, and nickel-tin. The copper-zinc alloys are used to coat steel wire used in tire-cord. Lead-tin alloys are known as terneplate and have many corrosion resistant applications. 

Selection of Zinc and Zinc-Alloy (Hot-Dipped and Electrodeposited) Coated Steel Sheet Tests and Procedures for SAE Low-Carbon Steel and Copper Nickel Tubing Guidelines for Usage of Stainless Steel and Bimetal for Exterior Automotive Bright Trim Cosmetic Corrosion Lab Test... 

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