Silver alloy electrodeposition

Sturzenegger B, Puippe JC (1984) Electrodeposition of palladium-silver alloys from ammoniacal electrolytes. Platinum Met Rev 20 117-124... 

Jewelry and silverware. Because of its high reflectivity, sterling silver (i.e., a silver-copper alloy) is extensively used for jewelry, silverware, and tableware where appearance is paramount. Sometimes, a protective rhodium coating is electrodeposited onto thin nickel-plated silver objects to avoid tarnishing. Sterling-silver alloy contains roughly 92.5 wt.% Ag, the remainder being copper or some other metals. 

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. 

Krastev, I. and Koper, M. T. M. (1995) Pattern-formation during the electrodeposition of a silver antinomy alloy. Phys. A, 213, 199-208. 

Bulk Ag-Al alloys, containing up to 12 a/o Al, were electrodeposited from melt containing benzene as a co-solvent. Examination by x-ray diffraction (XRD) indicated that the low-Al deposits were single-phase fee Ag solid solutions whereas those approaching 12 a/o were two-phase, fee Ag and hep i>-Ag2Al. The composition at which ti-Ag2Al first nucleates was not determined. The maximum solubility of aluminum in fee silver is about 20.4 a/o at 450 °C [20] and is reduced to about 7 a/o at room temperature. One would expect the lattice parameter of the fee phase to decrease only slightly when aluminum alloys substitutionally with silver because the... 

Between 1980 and about 2000 most of the studies on the electrodeposition in ionic liquids were performed in the first generation of ionic liquids, formerly called room-temperature molten salts or ambient temperature molten salts . These liquids are comparatively easy to synthesize from AICI3 and organic halides such as Tethyl-3-methylimidazolium chloride. Aluminum can be quite easily be electrode-posited in these liquids as well as many relatively noble elements such as silver, copper, palladium and others. Furthermore, technically important alloys such as Al-Mg, Al-Cr and others can be made by electrochemical means. The major disadvantage of these liquids is their extreme sensitivity to moisture which requires handling under a controlled inert gas atmosphere. Furthermore, A1 is relatively noble so that silicon, tantalum, lithium and other reactive elements cannot be deposited without A1 codeposition. Section 4.1 gives an introduction to electrodeposition in these first generation ionic liquids. 

Fig. 5.5 Plan-view SEM images of silver wire samples that have been electrodeposited with 12.73Ccrrr2 of zinc followed by de-alloying at 0.6 V. The amounts of the zinc that was de-alloyed are (a) 1.59, (b) 4.77, (c) 9.55, and (d) 12.73 Ccm-2. The temperature was 150°C. [Ref. 35].

In addition, ILs could also be used as both solvent and electrolyte for the electrodeposition of copper [35, 36], aluminum [37, 38], tantalum [4], platinum [39], silver [40, 41], gold [40-42], and silicon [43]. For example, Endres et al. have reported the electrodeposition of nanocrystalline metals and alloys, such as aluminum from ILs, which previously could not be electrodeposited from aqueous or organic solutions. This method enabled the synthesis of aluminum nanocrystals with average grain sizes of about 10 nm, Al-Mn alloys, as well as Fe and Pd nanocrystals [4] [as shown in Fig. 4.2). 

Dobrovolska TS, Krastev I, Zielonka A (2010) Pattern formation in electrodeposited Silver-Cadmium alloys. ECS Trans 25 1-9... 

Kristev I, Nikolova M (1986) Structural effects during the electrodeposition of silver-antimony alloys from ferrocyanidethiocyanate electrolytes. J Appl Electrochem 16 875-878... 

Tungsten-copper-boron nitride pseudoalloy electrodes have been tested in electric discharge machining of hard alloys [101,102]. Alloys used in the manufacture of electric contacts are frequently composites of metals and a-BN, providing for increased heat durability [103]. Thus, silver cermet electrical contact material for circuit breakers is made by hot-pressing of the constituents [104 to 106]. Again, Ag/BN composite layers can also be prepared by electrodeposition [107]. Zinc alloys as used in coating sheet steel as anticorrosion layers may contain dipersed a-BN for increased weldability and corrosion resistance [108 to 111]. 

Figure 11.1 Rotating spiral waves during the electrodeposition of silver-antimony alloy. The characteristic wavelength (i.e., the pitch) and the rotation period of the spiral waves are 10 lm and 10 s, respectively. Reprinted with permission from Ref [11].

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