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Electrowinning, the extraction of metal from ores [2] Electrorefining, the purification of metals. [2] Metal powder production by electrodeposition is included in this category, or sometimes electrowinning, or a separate category depending on application. [2] Electroplating, the deposition of a layer of one metal on another [2]
Chemical coloring of metals is the process of changing the color of metal surfaces with different chemical solutions. The chemical coloring of metals can be split into three types: electroplating – coating the metal surface with another metal using electrolysis. patination – chemically reacting the metal surface to form a colored oxide or ...
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current.
In some cases, it is desirable to co-deposit two or more metals resulting in an electroplated alloy deposit. Depending on the alloy system, an electroplated alloy may be solid solution strengthened or precipitation hardened by heat treatment to improve the plating's physical and chemical properties. Nickel-Cobalt is a common electroplated alloy.
The metal is deposited on the cathode. In a practical sense, this idealized process is complicated by some or all of the following considerations: the metal content is low (a few percent is typical), other metals deposit competitively with the desired one, the ore is not easily or efficiently dissolved.
Chrome plating (less commonly chromium plating) is a technique of electroplating a thin layer of chromium onto a metal object. A chrome plated part is called chrome, or is said to have been chromed. The chromium layer can be decorative, provide corrosion resistance, facilitate cleaning, and increase surface hardness. Sometimes a less expensive ...
Certain metals, such as zinc, may become embrittled from the hydrogen gas which is evolved at the cathode. The anodic process avoids this effect since oxygen is being generated at the anode. The major advantages that are normally touted for the cathodic processes are: Higher levels of corrosion protection are possible.
Before plating, the surface of the material must be thoroughly cleaned. Unwanted solids left on the surface cause poor plating. Cleaning is usually achieved by a series of chemical baths, including non-polar solvents to remove oils and greases, as well as acids and alkalis to remove oxides, insoluble organics, and other surface contaminants.