Galvanization or galvanisation refers to any of several electrochemical processes named after the Italian scientist Luigi Galvani.
The first commercial use of galvanised sheet metal was for the Baldwin Brother's Gleaner combine harvester.
Originally, galvanization was the administration of electric shocks (in the 19th century also termed Faradism, after Michael Faraday). It stemmed from Galvani's induction of twitches in severed frogs' legs, by his accidental generation of electricity. This archaic sense is the origin of the meaning of galvanic when meaning "affected/affecting, as if by a shock of electricity; startled".[1] Its claims to health benefits have largely been disproven, except for some limited uses in psychiatry in the form of electroconvulsive therapy (ECT). Later the word was used for processes of electrodeposition. This remains a useful and broadly applied technology, but the term "galvanization" has largely come to be associated with zinc coatings, to the exclusion of other metals.
In current use, it typically means hot-dip galvanizing, a metallurgical process that is used to coat steel or iron with zinc. This is done to prevent galvanic corrosion (specifically rusting) of the ferrous item; while it is accomplished by non-electrochemical means, it serves an electrochemical purpose.
Hot-dip galvanized steel has been effectively used for more than 150 years. The value of hot-dip galvanizing stems from the relative corrosion resistance of zinc, which, under most service conditions, is considerably better than iron and steel. In addition to forming a physical barrier against corrosion, zinc, applied as a hot-dip galvanized coating, cathodically protects exposed steel. Furthermore, galvanizing for protection of iron and steel is favored because of its low cost, the ease of application, and the extended maintenance-free service that it provides.
Although galvanizing will inhibit attack of the underlying steel, rusting will be inevitable, especially if the local rainfall is at all acidic in nature. So for example, corrugated iron sheet roofing will start to degrade within a few years despite the protective action of the zinc coating. Marine environments also lower the lifetime of galvanized iron roofs and similar products, because the high electrical conductivity of sea water encourages and increases the rate of corrosion. Corrugated steel roofs can last for many years if further protected by a paint layer. Galvanized car frames may also be at risk, especially where road salting is used extensively.
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