Electrochemical deposition of metals

Material Protection. The graft copolymers of ethylene sulfide on polyethyleneimine can be used as an antifouHng anticorrosion substrate for iron (439). PEIs or their derivatives are also used in electrolysis baths as brighteners in the electrochemical deposition of metals (440,441). 

Such behavior is similar in this respect to the electrochemical deposition of metal on a foreign substrate, in which an overpotential is required for nucleation, after which further growth of the metallic layer occurs at the characteristic redox potential of the metal, leading to a trace-crossing in the reverse sweep. However, recent voltammetric studies have shown that such trace-crossings still appear even if deposition processes or insoluble film formation cannot be detected... 

Electrochemical deposition of metals and alloys involves the reduction of metal ions from aqueous, organic, and fused-salt electrolytes. In this book we treat deposition from aqueous solutions only. The reduction of metal ions in aqueous solution is... 

Kinetic Scheme. Generally, metal ions in a solution for electroless metal deposition have to be complexed with a ligand. Complexing is necessary to prevent formation of metal hydroxide, such as Cu(OH)2, in electroless copper deposition. One of the fundamental problems in electrochemical deposition of metals from complexed ions is the presence of electroactive (charged) species. The electroactive species may be complexed or noncomplexed metal ion. In the first case, the kinetic scheme for the process of metal deposition is one of simple charge transfer. In the second case the kinetic scheme is that of charge transfer preceded by dissociation of the complex. The mechanism of the second case involves a sequence of at least two basic elementary steps ... 

The electrochemical deposition of metal (Cd, Zn, Pb) from Me(II)-ethylenedia-minetetraacetic acid (EDTA) complexes... 

Chemical and Electrochemical Deposition of Metal Oxide Thin Films... 

A. Hovestad, Electrochemical Deposition of Metal Matrix Composites, PhD thesis, Eindhoven University of Technology (1997). 

During electrochemical deposition of metal oxides, metal hydroxides and metals, current are passed between an anode and cathode in a cell containing weakly alkaline electrolyte. The anion of the electrolyte is such that it does not form an insoluble salt with the metal anode. Metal ions issuing from the metal anode make contact with hydroxyl ions in solution and form finely divided oxides or hydroxides. The oxides or hydroxides are removed and chemically reduced to finely divided metal particles. The voltage necessary for carrying out the oxidation of the metal to metal ions is reduced through the use of an electrode as cathode, thereby reducing the cost of the process. 

Electrodeposition or electrochemical deposition (of metals or alloys) involves the reduction of metal ions from electrolytes. At the cathode, electrons are supplied to cations, which migrate to the anode. In its simplest form, the reaction in aqueous medium at the cathode follows the equation ... 

In 1963 Dr. Danbk joined the Institute of Inorganic Chemistry of the Slovak Academy of Sciences in Bratislava, of which he was the director in the period 1991-1995. His main field of interest was the physical chemistry of molten salts systems in particular the study of the relations between the composition, properties, and structure of inorganic melts. He developed a method to measure the electrical conductivity of molten fluorides. He proposed the thermodynamic model of silicate melts and applied it to a number of two- and three-component silicate systems. He also developed the dissociation model of molten salts mixtures and applied it to different types of inorganic systems. More recently his work was in the field of chemical synthesis of double oxides from fused salts and the investigation of the physicochemical properties of molten systems of interest as electrolytes for the electrochemical deposition of metals from natural minerals, molybdenum, the synthesis of transition metal borides, and for aluminium production. 

ELECTROCHEMICAL DEPOSITION OF METAL SELENIDE CLUSTERS ON SELENIUM SURFACE... 

One of the most effective methods to prevent corrosion is to isolate the substrate from corrosive environments by means of a corrosion-resistant coating. In this way, ILs have been extensively studied and used as electrolyte during the electrochemical deposition of metals to obtain metallic protective films against corrosiOT [3-5]. But some ionic liquids can also form a corrosion-resistant thin film over a metallic substrate in absence of metal salt, as corrosion inhibitors. 

Day, D.A., Zook, A.L., Barshick, CM., Hess, K.R. (1997) Electrochemical deposition of metals in the preparation of standard materials for glow discharge mass spectrometry. Microchemical Journal, 55, 208-221. 

Less often, nanoparticles are formed on polymers by means of electrophoretic and electrochemical deposition of metals onto an added polymeric suspension. The metallopolymer formation results from the polarizational of polymer and metal particles during deposition on the electrode followed by chemisorption of macromolecules at the metal sinface at the moment of its reduction. This process includes... 

Porous silicon is a promising template for the preparation of metal nanostructures by eleetroehem-ical deposition. Because porous siheon is a semiconduetive porous electrode, eleetroehemieal deposition of metals oeeurs not only at the bottom of pores but also on the pore wall and pore openings. Thus, the control of electrochemical deposition within porous siheon has been a challenging issue. Eleetroehemieal deposition on porous siheon is influenced by illumination condihons. Metal deposition on porous siheon is possible by displacement deposihon. Many studies have reported on electrochemical deposition of metal for prachcal appheations. In this chapter, electrodeposition under polarization is firstly reviewed. Secondly, displacement deposition on porous siheon is explained. Finally, the microscopic structure formation by electrodeposition on porous siheon is summarized. 

Oskam J, Long JG, Natarajan A et al (1998) Electrochemical deposition of metals onto silicon. J Phys D Appl Phys 31 1927-1949... 

Electrochemical deposition of metals in the pores of templating membranes requires that one side of the membrane be in direct contact with a metallic layer. This can be produced by plasma or vacuum deposition of a metal layer on one side of the membrane (25) and requires that the membrane film be robust enough to tolerate this kind of manipulation. The thickness of the conductive layer is typically 100-1000 nm (45-47). The metal which produces the conductive layer can be the same or different from the one that will provide the final template structure. In electrochanical template deposition, the coated film is placed in an electrochemical ceU where the template membrane acts as the cathode and a counter electrode is the anode. The deposition can be carried out under galvanostatic or... 

The main act of the electrochemical process, charge transfer, is localized in a very thin double electric layer. This process can take place continuously only when electrically active particles, that is, particles that participate in the charge transfer step are transferred toward the electrode, and the products formed move in the opposite direction - from the surface of the metal phase of the electrode to the solution volume. When electrochemical deposition of metal takes place in simple (noncomplex) salt solutions, there may be no transport of the product, because the metal atoms formed do not participate in the diffusion process, and they form a new solid phase - a crystal lattice. 

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