Electrolytic deposits, factors affecting

Actually, it is recognized that two different mechanisms may be involved in the above process. One is related to the reaction of a first deposited metal layer with chalcogen molecules diffusing through the double layer at the interface. The other is related to the precipitation of metal ions on the electrode during the reduction of sulfur. In the first case, after a monolayer of the compound has been plated, the deposition proceeds further according to the second mechanism. However, several factors affect the mechanism of the process, hence the corresponding composition and quality of the produced films. These factors are associated mainly to the com-plexation effect of the metal ions by the solvent, probable adsorption of electrolyte anions on the electrode surface, and solvent electrolysis. 

There are two major factors which have to be considered in the process of electrochemical metal deposition. First, thermodynamics and growth properties of 2D Me and 3D Me phases can be treated in a similar manner to that for Me deposition from vapor or electrolyte phases. Second, the properties of the electrolyte phase strongly affect the structure of the substrate/electrolyte interface, the kinetics of the mass and charge transfer across it, and the kinetics of chemical reactions which can precede or follow the charge transfer. 

Factors affecting number, size, and distribution of holes are (a) regime of electrolysis, (b) preparation of working electrode, (c) concentration of the depositing (Cu ) ions, (d) concentration of the supporting electrolyte (H2SO4), (e) temperature of electrolysis, and (f) time of electrolysis. 

Electrodeposition has the ability to produce a relatively uniform distribution of metal upon a cathode of irregular shape. Though the uniformity depends on the distribution of electric fields inside the electrolyte toward the surface of the electrode, other important factors have to be considered. The addition of agents (additives) to the electrolyte, for example, can affect the microscopic mechanism of electrodeposition, reducing the roughness of the deposit and producing a visual effect known as brightening. 

Macrothrowing power predicts the ability of an electrolyte to lay down as nearly as possible a uniformly thick deposit across the surface of a workpiece. A good covering power is a prerequisite for good macrothrowing power. Other factors that affect macrothrowing power include the current distribution and current density, electrolyte composition, electrolytic conductance, and electrolyte agitation. 

It is necessary to note that the abundance of zinc ions in the electrolyte (O.IM) only slightly affects the deposition rate. It seems possible to explain this fact by competition of the two factors zinc codeposition (positive) and mass transfer retardation due to evacuation of zinc ions from microanodes (negative). It allows us to conclude that the processes of tin and zinc reduction and dissolution are repeated many times while the tin film is growing. Such peculiarity of tin cementation in zinc has the principal effect on the nuclei growth and coalescence and, consequently, on film microstructure. 

Polypyrrole and many of its derivatives can be synthesized via simple chemical or electrochemical methods [120]. Photochemically initiated and enzyme-catalyzed polymerization routes have also been described but less developed. Different synthesis routes produce polypyrrole with different forms chemical oxidations generally produce powders, while electrochemical synthesis leads to films deposited on the working electrode and enzymatic polymerization gives aqueous dispersions [Liu. Y. C, 2002, Tadros. T. H, 2005 and Wallace. G. G, 2003]. As mentioned above the electrochemical polymerization method is utilized extensively for production of electro active/conductive films. The film properties can be easily controlled by simply varying the electrolysis conditions such as electrode potential, current density, solvent, and electrolyte. It also enables control of thickness of the polymers. Electrochemical synthesis of polymers is a complex process and various factors such as the nature and concentration of monomer/electrolyte, cell conditions, the solvent, electrode, applied potential and temperature, pH affects the yield and the quality of the film... 

When ionic liquid systems are intended to be applied for electrodepwsition their behaviour has to be assessed as comp>ared with the case of aqueous electrolytes. The main factors which affect the overall electrochemical process include viscosity, conductivity, the potential window, the ionic medium chemistry as well as the structure of the electrical double layer and redox potentials. All these prarameters will influence the diffusion rate of metallic ions at the electrode surface as well as the thermodynamics and kinetics of the reduction process. Consequently, the nudeation/growth mechanisms and the deposit morphology will be affected, too. More detailed discussions on this topic may be formd in ( Abbott et al., 2004 Abbott et al., 2004 Abbott McKenzie, 2006 Abbott et al., 2007 Endres et al., 2008 and included references). 

Being located in a desert (arid) climate, Kuwait is affected by many dust storms during the year and especially during the summer and spring. The amount of dust in the atmosphere and its composition are variable and depend on many factors. Deposition of dust on metal surfaces is pronounced in the initial stages because of the action of soluble electrolyte-forming components in reducing the critical humidity... 

In designing layered nanostructures, deposited material forms continuous layers but to achieve the same, deposition must take place in a very controlled manner. Moreover, factors such as temperature, pH of the electrolyte, electrolyte concentration, current density, and deposition time must be kept in mind as they greatly affect the quality of the material deposited. 

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