Corrosion

Corrosion, gradual destruction of a substance, usually a metal, by chemical action. Oxidation is the most common form of corrosion. Rusting of structures made of iron is a familiar example. Corrosion can dangerously weaken structures. The simplest precaution consists of coating the metal with protective layers of paint. Sometimes iron is coated with another metal, notably zinc, to produce galvanized iron. Plastic coatings have recently been developed to prevent corrosion. In jet engines and nuclear devices corrosion is a particularly difficult problem, since the metals used are subjected to high temperatures and stresses in circumstances where mechanical failure through corrosion could be disastrous. Radiation may also increase susceptibility to corrosion and also change the mechanical properties of the metal. Special alloys have been developed to overcome these difficulties.

See also: Oxidation; Reduction.