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Galvanic Corrosion and Galvani

The bimetallic driving force causing galvanic corrosion was discovered in the late part of the eighteenth century by Luigi Galvani in a series of experiments with the exposed muscles and nerves of a frog that contracted when connected to a bimetallic conductor. The principle was later put into a practical application by Alessandro Volta who built, in 1800, the first electrical cell, or battery: a series of metal disks of two kinds, separated by cardboard disks soaked with acid or salt solutions. This is the basis of all modern wet-cell batteries, and it was a tremendously important scientific discovery, because it was the first method found for the generation of a sustained electrical current.

The principle was also engineered into the useful protection of metallic structures by Sir Humphry Davy and Michael Faraday in the early part of the nineteenth century. The sacrificial corrosion of one metal such as zinc, magnesium or aluminum is a widespread method of cathodically protecting metallic structures.

There has been some confusion regarding oxidation-reduction electromotive-force potentials and the galvanic series. While there are similarities between the galvanic series and standard reduction potentials, there are also some fundamental differences. While standard potentials can provide an indication of the stability of a metal, as it is done with E-pH or Pourbaix diagrams, galvanic series are used to predict whether or not galvanic corrosion will occur, and if so, which of the two coupled metals will exhibit increased corrosion. Thus, these two tabulations have entirely different uses and should therefore not be confused.