corrode

Corrode is a verb describing the deterioration of a material, most often a metal, due to chemical or electrochemical reactions with its surroundings. The most familiar example is rusting of iron and steel, the formation of iron oxides and hydroxides in the presence of water and oxygen. Corrosion is a natural, gradual process that can undermine strength, appearance, and function.

Corrosion can be electrochemical, requiring an electrolyte and electron transfer, or purely chemical. Electrochemical corrosion includes galvanic corrosion, where dissimilar metals in electrical contact accelerate the anodic metal, and localized forms such as pitting and crevice corrosion. Chemical corrosion proceeds when the metal reacts directly with a corrosive substance, such as acids, without the central role of electron transfer between metals.

Rate and form of corrosion depend on environmental factors (temperature, humidity, pH, oxygen, chloride content), material properties (alloy composition, microstructure, protective oxide films), and design features (dissimilar metals, crevices). Corrosion products vary by metal: iron forms oxides and hydroxides; aluminum forms a protective oxide; copper develops patina. Rates are often expressed as a corrosion rate or thickness loss per year.

Prevention and mitigation strategies include protective coatings, paints, or polymer films; corrosion inhibitors; cathodic protection using sacrificial anodes or impressed current; alloy selection with corrosion-resistant materials; and design changes to reduce crevices and avoid galvanic couples. Regular inspection and maintenance aid early detection and remediation.

Corrosion is a major concern in infrastructure, transportation, and industry, prompting ongoing research in materials science and corrosion-monitoring technologies. Microbiologically influenced corrosion recognizes the role of microorganisms in accelerating deterioration under certain conditions.