Bath composition

Black and colored plates can also be obtained from chromic acid baths. The plates are mostly oxides (177). Black chromium plating bath compositions are proprietary, but most do not contain sulfate. The deposit has been considered for use in solar panels because of its high absorptivity and low emissivity (175). 

Copper-plating bath compositions of various types have been used. A typical bath formulation consists of 200 g copper sulfate crystals, 30 mL cone, sulfuric acid, 2 mL phenylsulfonic acid, and 1000 mL distUled water. A pure copper anode may be used a copper anode containing a trace of phosphoms reduces sludge accumulation in the plating bath. 

Silver-plating bath compositions are somewhat variable a typical composition contains 36 g silver cyanide, 60 g potassium cyanide, 45 g potassium carbonate, and 1000 mL distilled water. A pure silver anode is required (179). 

Chromium. AppHcations of chromium plating can be separated into two areas hard chromium, also called functional, industrial, or engineering chromium, and decorative chromium. The plating bath compositions may be the same for both. In most cases, the differentiating factor is plate thickness. Decorative chromium is usually less than about 1 p.m hard chromium can be from about 1 p.m to 500 p.m or more. 

Acid Copper. Bath compositions are shown in Table 8. The acid sulfate bath is by far the most widely used copper plating bath, both for plating and for electroforming and electrowinning. The fiuoborate baths have been Htde used in spite of the high current densities possible. Additional information can be found in the Hterature (98,99). 

Nickel. Nickel plating continues to be very important. Many plating baths have been formulated, but most of the nickel plating is done in either Watts baths or sulfamate baths. Watts baths contain sulfate and chloride nickel salts along with boric acid, and were first proposed in 1916 (111). Nickel was first plated from sulfamate in 1938 (112) and patented in 1943 (108). The process was brought to market in 1950 (113). Typical bath compositions and conditions are shown in Table 14. 

These results are quite interesting. The initial stages of Al deposition result in nanosized deposits. Indeed, from the STM studies we recently succeeded in making bulk deposits of nanosized Al with special bath compositions and special electrochemical techniques [10]. Moreover, the preliminary results on tip-induced nanostructuring show that nanosized modifications of electrodes by less noble elements are possible in ionic liquids, thus opening access to new structures that cannot be made in aqueous media. 

Copper electrodeposition on Au(111) Copper is an interesting metal and has been widely investigated in electrodeposition studies from aqueous solutions. There are numerous publications in the literature on this topic. Furthermore, technical processes to produce Cu interconnects on microchips have been established in aqueous solutions. In general, the quality of the deposits is strongly influenced by the bath composition. On the nanometer scale, one finds different superstmctures in the underpotential deposition regime if different counter-ions are used in the solutions. A co-adsorption between the metal atoms and the anions has been reported. In the underpotential regime, before the bulk deposition begins, one Cu mono-layer forms on Au(lll) [66]. 

Succinic acid has also been proposed for the stabilisation of a selfregulating bath, a recommended bath composition consisting of 375 g/1 of CrOj, 8 g/1 of SrS04, and 40 g/1 of succinic anhydride the bath is... 

The combination of a positive charge and reducibility of tetrazolium salts finds use as anticorrosion agents for metals.634,635 The y are components of an oxidant/etchant bath composition for silicon dioxide corrosion-resistant surfaces.636 They are also used as antistatic agents in polyamide... 

Electrodeposition of metal onto structured objects, such as circuits, is controlled in part by a template. At the same time, the deposit must fill all the recesses uniformly and seamlessly, the texture and crystal structure must fall within tolerances, and the quality of the features must be sustained over a large workpiece. The distribution of material within recesses or onto widely separated portions of the workpiece is subject to a limited number of macroscopic control-parameters such as applied potential and plating bath composition. Success therefore depends on exploitation of the natural pathways of the process. The spontaneous and unconstrained development of structure must be taken into consideration in the production of highly organized and functional patterns. 

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. 

Bath Composition Particle Size and Crystal Phase Particle Loading (g/1) Current Density (mA/cm2) Analytical Method Codeposition Results ... 

Particles can be characterized by their composition and crystallographic phase, as well as by their size, density, and shape. The particle composition can have a dramatic impact on the amount of incorporation obtained for a particular bath composition. For instance three times more TiC>2 than AI2O3 has reportedly [54] been incorporated into a Ni matrix, under the same deposition conditions. 

Perhaps even more noteworthy is the effect of crystallographic phase. While one phase of a specific composition may readily incorporate from a particular bath composition, another phase of the same composition may incorporate to a much lower extent or not at all. For instance, in the alumina particle system, the alpha phase has been found to readily incorporate from an acidic copper bath while the gamma phase incorporates at less than one tenth the amount of alpha, if at all, as shown in Table 1 [2, 11, 27, 31, 33],... 

It was not until 1987, before a second model on electrocodeposition was published by Buelens [37, 58], From experimental observations on the codeposition of particles on a rotating disk electrode (RDE) as a function of current density, rotation speed and bath composition, that could not be explained by Guglielmi, she suggested that a particle will only be incorporated into the deposit if a certain amount of the adsorbed ions on the particle surface is reduced. This is one possible way to account for the field-assisted adsorption, held responsible for the transition between loosely and strongly adsorbed particles in the model of Guglielmi. This proposition yields the probability P(k/K,i) for the incorporation of a particle based on the reduction of k out of K ions, bound to its surface, at current density i... 

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. 

The reactions marked with an asterisk ) lead to lower effidences. (The conversion of ferrous to ferric, Eq. 6.8, usually takes place because of dissolved oxygen.) In order for the bath composition to remain constant, the rate of dissolution (Eq. 6.7) must equal the rate of deposition (Eq. 6.9). If they do not occur at the same rate this will lead to concentration polarisation which will act as a barrier to the electrode reactions. We have seen previously (Section 6.2) that ultrasound is able to reduce concentration polarisation. 

The effect of ultrasound has been extremely beneficial in improving the hardness of nickel deposits (Tab. 6.11). Using a variety of plating solutions it has been shown that the presence of ultrasound improves the hardness of the coating with the magnitude dependent on the particular bath composition employed [9,12]. 

Some bath compositions tend to have the property of decreasing the difference between the thinnest and thickest deposits. In other words, they give rise to uniform cathode coverage despite irregularities. Such solutions are referred to as having good throwing power. 

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