Electroplating
Electroplating is the coating of an electrically conductive item with a layer of metal using electrical current. The result is a thin, smooth, even coat of metal on the object.
Process
The process used in electroplating is called electrode position. The item to be coated is placed into a container containing a solution of one or more metal salts. The item is connected to an electrical circuit, forming the cathode (negative) of the circuit while an electrode typically of the same metal to be plated forms the anode (positive). When an electrical current is passed through the circuit, metal ions in the solution are attracted to the item. The result is a layer of metal on the item however considerable skill and craft-technique is required to assure an evenly-coated finished product. This process is analogous to a galvanic cell acting in reverse.
The plating is most commonly a single metallic element, not an alloy. However, some alloys can be electrodeposited, notably brass.
Industrial use
Electroplating is used in many industries for functional and/or decorative purposes.
Some well known examples are chrome-plating of steel parts on automobiles. Steel bumpers become more corrosion-resistant when they have been electroplated with first nickel and then chromium.
Steel camshafts resist wear better when they have been electroplated with chromium.
Steel bolts last much longer because they are sold with a coating of zinc that has been applied by electroplating.
Electroplating can be used to silver plate copper or brass electrical connectors, since silver tarnishes much slower and has a higher conductivity than those metals. The benefit of the silver is lower surface electrical resistance resulting in a more efficient electrical connection. Silver plating is also popular for RF connectors because radio frequency current flows primarily on the surface of its conductor; the connector will thus have the strength of brass and the conductivity of silver.
Electropainting
Electropainting is electrocoating, also known as electrophoretic painting, electro-painting or E-coat. It's an organic finish which is often applied as a prime coat on steel. The part is immersed in an electrified tank, and the reaction between the electricity and the solution causes the paint to deposit.