Electrodeposition

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electrodeposition

[i¦lek·trō‚dep·ə′zish·ən]
(metallurgy)
Electrolytic process in which a metal is deposited at the cathode from a solution of its ions; includes electroplating and electroforming. Also known as electrolytic deposition.

Electrodeposition

 

(also electrolytic deposition), the deposition of a metal or an alloy at a cathode during the electrolysis of a solution or melt of the respective salt.

Crystal growth during electrodeposition has much in common with crystallization from a vapor or a solution. The factor that governs supersaturation in electrodeposition is the overvoltage that occurs at an electrode during an electrochemical reaction. Depending on the magnitude of the overvoltage, crystal growth may occur by means of spiral growth on screw dislocations, the formation and growth of two-dimensional crystal nuclei, or—at high enough overvoltages—the formation of three-dimensional nuclei. The formation and growth of two-dimensional nuclei are typical of dislocationless crystals; the formation of three-dimensional nuclei is the normal process of crystal growth.

The possibility of varying the cathodic overvoltage over a wide range makes it possible to obtain metallic layers that have markedly different properties. Thus, depending on the formation conditions for deposits, the dislocation density in a deposit may range from 106 to 1012 cm–2. Consequently, such properties as conductivity, hardness, and ductility may also be varied. High dislocation densities have been found in deposits of, for example, copper, nickel, iron, chromium, platinum, and silver.

The adsorption of surfactants and the incorporation of impurities have an especially strong effect on the structure of the metallic deposits obtained by electrodeposition.

Electrodeposition is the basis of electrometallurgy, the refining of metals, and electroplating technology.

IU. M. POLUKAROV

References in periodicals archive ?
The Ni-P electrodeposits having different P content thus obtained were further investigated to study the effect of P content on the microstructure, surface morphology, and mechanical properties of the deposits.
Figure 11 shows the surface morphology of Ni-P electrodeposits with different P contents.
A steady decrease in the modulus of the electrodeposits is observed when the concentration of [H.
Electrodeposits of Ni-P having desired P content can be obtained by the careful selection of bath composition and plating parameters.
WC, "Structural Evolution and Internal Stress of Nickel-Phosphorous Electrodeposits.
At a minimum, the results for the whiskerless tin chemistry and the reflowed matte tin finish would suggest that electrodeposit properties and characteristics could be manipulated such that an otherwise whisker resistant type of finish whiskers quite readily.
The size, growth direction and proximity of these whiskers to the surface of the deposit may suggest a different level of risk to device performance for these whiskers than those from the other two types of electrodeposit.
A given electrodeposit could robustly withstand many months in a particular environment without whiskering, yet in a relatively short span of time with a one-factor modification of the aging environment the same deposit could suddenly experience significant whisker initiation and growth.
The whiskering performance of a particular finish is known to depend strongly on a variety of factors, including surface oxide condition, electrodeposit thicknesses, composition of the barrier layer, level of residual stress, temperature and time.
The Corrosion Behaviour of Nanocrystalline Electrodeposits.
Papaioannou, JC, "Impedance Spectroscopy Study of Nickel Electrodeposits.
Anodic sweeping voltammetry analysis is employed effectively for the in situ characterization of the electrodeposition process and products of the galvanostalically obtained electrodeposits on the steel substrate.