'''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
electrodeposition. 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
anode or the
cathode of the circuit. When an electrical current is passed through the circuit, metal
ions in the solution are attracted to the item. The result is an evenly-coated layer of metal around the item. 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. It 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 RF
current flows primarily on the surface of its conductor; the connector will thus have the strength of brass and the conductivity of silver.
History
Modern history
Modern electroplating was invented by Italian chemist Luigi V. Brugnatelli in 1805. Brugnatelli used his colleague
Alessandro Voltas invention of five years earlier, the voltaic pile, to facilitate the first electrodeposition. Unfortunately, Brugnatellis inventions were repressed by the French Academy of Sciences and did not become used in general industry for the following thirty years.
By 1839, scientists in
Britain and
Russia had independently devised metal deposition processes similar to Brugnatelli's for the copper electroplating of
printing press plates. Soon after,
John Wright of Birmingham, England discovered that potassium cyanide was a suitable electrolyte for gold and silver electroplating. Wright's associates,
George Elkington and Henry Elkington were awarded the first patents for electroplating in 1840. These two then founded the electroplating industry in Birmingham England from where it spread around the world.
Prehistory
A number of artifacts known as the
Baghdad Battery were found near Baghdad, Iraq, and were speculated to have been crude
galvanic cells used for electroplating. The exact age of the artifacts is not known, but they are believed to be either Parthian or Sassanian. The theory that they were used for electroplating is not widely held today, even by those who believe that the artifacts were in fact electrical devices.
Miscellaneous
One of American physicist
Richard Feynmans first projects was to develop technology for electroplating metal onto plastics. Feynman successfully developed this technology, allowing his employer to keep commercial promises he had made but couldnt have fulfilled otherwise.
On
June 28, 1988, four workers at an electroplating plant in
Auburn, Indiana were asphyxiated by hydrogen cyanide gas produced when muriatic acid was mixed with zinc cyanide in a cleaning operation. A fifth victim died two days later.
External links and sources
Electrochemistry Encyclopedia article
Category:Chemical processes
Category:Industrial processes
nl:elektrodepositie