Electro-deposition

Characteristic Evaporation Ion plating Sputtering Chemical vapor deposition Electro- dep 0 sitio n Thermal spraying... 

Electroforming. The reproduction of an object or a pattern by electro deposition (See under Electrochemistry). A mold of the object to be reproduced is made in a soft metal or in wax (by impression). The non-conductor mold surface is made conductive by coating with graphite. Some suitable metal is then deposited electro lyrically on the mold surface. This mold is then (in most cases) a negative of the object to be produced. Most extensive use is in the phonograph record industry Ref GondChemDicc (1961), 434-R... 

The Electrodeposition of Metals.—If hydrogen were evolved at a cathode at its reversible potential under all conditions no metal higher in the electromotive series than hydrogen could be deposited electro-lytically from an aqueous solution. Due to hydrogen overvoltage, however, it is possible to obtain deposits of these metals as high in the... 

Crystallization — The process of forming solid crystals from solution, melted or polycrystalline phase. Used to separate solid and liquid phase or preparing high purity materials. Crystallization from solution is the most common example of solid-liquid separation. In the process, the solid crystals are formed from supersaturated solution (the solution that contains more soluble molecules, ions etc. that it would under equilibrium conditions). Usually the supersaturated solution is obtained either by cooling the solution, evaporating the solvent, pH change, or adding another solvent. The crystallization process can be induced electrochemically (- electro deposition, electro crystallization). The most common ex-... 

Yoshino, K. Ebina, N. Proc. Sym. Electroless Metal Deposition, Electro-chem. Soc. 88-12,1988, p 268. 

This use was founded on the fact that KCN possesses the property of dissolving the salts of metals like gold, silver, and nickel, etc., the metal going into solution as a double cyanide. From these solutions the metal can be readily deposited electro-chemically in a coherent layer by making the surface of the object to be coated with the precious metal the negative pole in a solution of the double cyanide. 

Development of fractal patterns during electro-deposition Electro-deposition has for a long time been one of the most familiar aggregation phenomena in chemistry. Electro-deposition is a typical example of far from equilibrium growth phenomena governed by diffusion [44, 45]. A number of different morphologies developed by the... 

It has been established experimentally that the number of nuclei deposited electro-lytically onto an inert electrode increases linearly with time after an induction period. After a sufficient length of time, it reaches a saturated value that is independent of time. The density of the saturation value increases with the increasing applied overpotential and is strongly dependent on the concentration of the electrolyte and the state of the electrode surface [55]. 

A particle obtained by tapping of the copper deposit electro-deposited at an overpotential of 1,000 mV is shown in Fig. 3.10a. Channel stmcture generated through the interior of the particle by the simultaneous copper nucleation and strong hydrogen evolution in situ can easily be seen from Fig. 3.1 Oa. This type of powder consists of an aggregate of small cauliflower-like particles (Fig. 3.10b). Top view of the powder shown in Fig. 3.10a clearly revealed its... 

Chemically synthesized Cu(II)-containing PMT is used as the working electrode of a 3-electrode system in a thin layer amperometric cell unit to detect ionic analytes in an aqueous stream by flow injection analyses. The electrode response is linearly dependent on the applied voltage. The electrode possesses favorable sensitivity and stability in comparison to other metallic electrodes such as steel and platinum [794]. The incorporation of mercury into PMT results in an effective electrode for the analyses for lead(II) ions in aqueous media (detection limit 0.05 ppm). The mercury films are deposited electro-chemically after the electropolymerization step [795]. 

Another problem limiting the application of nanociystalline materials is prep>aration of nanocrystalline alloys. Currently, the bulk metallic nanomaterials can only be prepared at the laboratory scale, usually by compacting prepared nanocrystalline powders. However, consolidation of the nanopowders into bulk materials needs high temperature and pressure which may considerably coarsen the structure. Because of this difficulty, surface nanocoating has been considered a potential industry application. Nanocrystalline costing are often prepared by chemical vapour deposition (CVD), physical vapour deposition (PVD), electrochemical deposition, electro-spark deposition, and laser and electron beam surface treatment. 

T. J. Marks and P. Zhu, Vapor deposited electro-optic films self-assembled through hydrogen bonding, (Northwestern University, USA). 2004, 2004-US6249... 

Electro-deposition Electro-deposition as described by Taylor et al. (1992) and Gottesfeld and Zawodzinski (1997) involves impregnation of the porous carbon structure with ionomer, exchange of the cations in the ionomer by a cationic complex of platinum and electrodeposition of platinum from this complex onto the carbon support. This results in deposition of platinum only at sites that are accessed effectively by both carbon and ionomer. 

Electrogalvanizing Electrography Electrogravimetry Electrohydrodynamics Electro-Katadyn process Electrokinetics Electroless deposition Electroless nickel Electroless plating... 

Dispersion Resins. Polytetrafluoroethylene dispersions in aqueous medium contain 30—60 wt % polymer particles and some surfactant. The type of surfactant and the particle characteristics depend on the appHcation. These dispersions are appHed to various substrates by spraying, flow coating, dipping, coagulating, or electro depositing. 

Ion implantation (qv) has a large (10 K/s) effective quench rate (64). This surface treatment technique allows a wide variety of atomic species to be introduced into the surface. Sputtering and evaporation methods are other very slow approaches to making amorphous films, atom by atom. The processes involve deposition of a vapor onto a cold substrate. The buildup rate (20 p.m/h) is also sensitive to deposition conditions, including the presence of impurity atoms which can faciUtate the formation of an amorphous stmcture. An approach used for metal—metalloid amorphous alloys is chemical deposition and electro deposition. 

Electroforrning, which is used in the production of art objects or jewelry is a combination of electroless plating and electro deposition. A wax mold of the object to be produced is made conductive by electroless gold plating, a thick layer of gold or gold alloy is then electrodeposited and, finally, the wax is removed by melting (134). 

Electrometallurgy. A term covering the various electrical processes for the working of metals, eg, electro deposition, electrorefining and electro winning, and operations in electric furnaces. 

Wrought and cast nickel anodes and sulfur-activated electrodeposited rounds are used widely for nickel electro deposition onto many base metals. 

Nickel also is deterrnined by a volumetric method employing ethylenediaminetetraacetic acid as a titrant. Inductively coupled plasma (ICP) is preferred to determine very low nickel values (see Trace AND RESIDUE ANALYSIS). The classical gravimetric method employing dimethylglyoxime to precipitate nickel as a red complex is used as a precise analytical technique (122). A colorimetric method employing dimethylglyoxime also is available. The classical method of electro deposition is a commonly employed technique to separate nickel in the presence of other metals, notably copper (qv). It is also used to estabhsh caUbration criteria for the spectrophotometric methods. X-ray diffraction often is used to identify nickel in crystalline form. 

Plating and Coatings. Thin surface coatings of platinum and platinum alloys are used as decorative finishes and in critical appHcations where it is necessary to provide finishes resistant to corrosion or high temperature, eg, coatings on jet-engine turbine components (258). Compounds used in the electro deposition of platinum are based on Pt(Il) and Pt(IV) and include H2[PtCl3] and its salts, eg, Pt—P—Salt, [Pt(NH3)2(N02)2] H2[Pt(S04)(N02)2] ... 

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