Electrolyte-bath composition

The electrodeposited Bi2Sr2CaiCu2Ox (BSCCO) precursor films were obtained by co-electrodeposition of the constituent metals using nitrate salts dissolved in DMSO solvent. The electrodeposition was performed in a closed-cell configuration at room temperature ( 24°C). The cation ratios of the electrodeposition bath were adjusted systematically to obtain BSCCO precursor compositions. A typical electrolyte-bath composition for the BSCCO films consisted of 2.0-g Bi(N03)3-5H20,1.0-g Sr(N03)2, 0.6-g Ca(N03)2-4H20, and 0.9-g Cu(N03)2-6H20 dissolved in 400 mL of DMSO solvent. The substrates were single-crystal LAO coated with 300 A of Ag. 

From the research on electrocodeposition to date, a number of variables appear to be influential in the process, which include hydrodynamics, current density, particle characteristics, bath composition, and the particle-bath interaction. The influence that a particular variable has on the process is typically assessed by the change in the amount of particle incorporation obtained when that variable is adjusted. Although the effect of each of these process variables has been reported in the literature, the results are often contradictory. The effects of the process variables, of which many are interrelated, can also vary for different particle-electrolyte systems and electrodeposition cell configurations used. This review will summarize these effects and the contradictions in the literature on electrocodeposition. 

The composition of the codeposition bath is defined not only by the concentration and type of electrolyte used for depositing the matrix metal, but also by the particle loading in suspension, the pH, the temperature, and the additives used. A variety of electrolytes have been used for the electrocodeposition process including simple metal sulfate or acidic metal sulfate baths to form a metal matrix of copper, iron, nickel, cobalt, or chromium, or their alloys. Deposition of a nickel matrix has also been conducted using a Watts bath which consists of nickel sulfate, nickel chloride and boric acid, and electrolyte baths based on nickel fluoborate or nickel sulfamate. Although many of the bath chemistries used provide high current efficiency, the effect of hydrogen evolution on electrocodeposition is not discussed in the literature. 

Extensive work has been devoted to aluminum electroplating in nonaqueous systems. Choosing appropriate bath compositions enables aluminum to be deposited at high efficiency and purity from nonaqueous electrolyte solutions. Comprehensive reviews on this matter have appeared recently in the literature [123,455], This work has led to the development of a number of commercial processes for nonaqueous electroplating of aluminum. The quality of the electroplated aluminum is very similar to that of cast metal. For instance, electrodeposited aluminum can be further anodized in order to obtain hard, corrosion resistive, electrically insulating surfaces. It is also possible to electroplate A1 on a wide variety of metal surfaces, including active metals (e.g., Mg, Al), nonactive metals, and steel. 

The mechanism of particle incorporation is treated extensively in the next section, but a generalized mechanism is given here to better comprehend the effects of the process parameters. Particle incorporation in a metal matrix is a two step process, involving particle mass transfer from the bulk of the suspension to the electrode surface followed by a particle-electrode interaction leading to particle incorporation. It can easily be understood that electrolyte agitation, viscosity, particle bath concentration, particle density etc affect particle mass transfer. The particle-electrode interaction depends on the particle surface properties, which are determined by the particle type and bath composition, pH etc., and the metal surface composition, which depends on the electroplating process parameters, like pH, current density and bath constituents. The particle-electrode interaction is in competition with particle removal from the electrode surface by the suspension hydrodynamics. 

The most extensive research results concern the hydride electrolyte system 2 [13-16, 68, 78, 82, 92, 93, 102, 209]. With the help of Raman spectroscopic measurements, the chemical constituents of the electrolyte were determined and the electrode reactions examined with chronoamperometric methods [82]. The catalytic role of hydride and the role of neutral and ionic aluminum components were thus detected. The dependence of the polarization parameters on the electrolyte composition shows a marked maximum from which the bath composition with the highest current distribution can be determined. The influence of the temperature and the composition on the electrode process kinetics was studied by Badawy et al. [13-16]. The results of Eckert et al. [68] show a dependence of the activation energy on the electrolyte composition of the hydride baths. The first electrochemical investigation results with respect to type 3 aluminum alkyl electrolyte were obtained by Kautek et al. [100, 101] and Tabataba-Vakili [186, 187, 133]. 

Electrolyte bath resistivity, at 950°C Current efficiency, 100 kA cells Normal energy efficiency Typical anode gas composition ... 

It should be mentioned here that the composition of the electrolyte solution used in these in situ STM studies of the electrochemical deposition of noble metals (platinum, palladium, rhodium and ruthenium) are quite different from those used in the real electroplating industry [56-58]. Although some experimental conditions (temperature, concentration) may be difficult for the in situ STM measurements, electrodeposition in a practical electrolyte bath should provide more information both in application and in fundamental fields. 

The composition and structure of the coating membranes can easily be modified through control of the chemical and electrochemical parameters of the electrolytic bath. This allows model studies of the response mechanism. 

The probability can be expressed by the equilibrium constants and ion concentrations in the electrolyte bath by insertion of the relations (8.32) for the active atoms in the kink site positions in Eq. (8.33a-d). The relation between the alloy composition and electrolyte concentration is derived by the procedure described in Section 8.6.1. 

CAS 89-08-7 EINECS/ELINCS 201-881-6 Uses Electrolytic bath additive for production of hard anodic oxide coatings on aluminum and aluminum-based alloys colored coalings are abrasion resist, and attractive for architectural and other uses Features Colors depend on base metal composition, current dens., voltage, film thickness and electrolyte composition, particularly sulfate and aluminum contents Properties 49-51% act. 

Results depend upon pre-cleaning of the surface, bath composition, current density and operating temperature. For steel, the electrolyte can be 75% H3PO4 at 65°C, although mixtures with sulphuric and/or chromic acids are also used. 

The co-deposition of microparticles with metal ions in an electrolytic bath under the influence of electric field to form a composite plating coating containing those microparticles. 

The biggest application for fiuorinated ionomers currently is as unreinforced membranes for fuel cells, or polytetrafluoroethylene (PTFE) fiber-reinforced composite membranes for electrolytic baths. The membranes can be fabricated by the extrusion method or the solution-cast method. 

In contrast to the electrolytic process, the nickel ions are reduced with the aid of a chemical reducing agent (sodium phosphinate, NaH2P02> from an aqueous bath. Other elements can be deposited as well as nickel. By varying the bath composition and temperature, special coating compositions (e.g. phosphorus 2 to 15%) can be achieved with different properties. 

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