Korroosion

Korroosion is the deterioration of materials, typically metals, due to chemical or electrochemical reactions with their environment. It is an electrochemical process in which the metal loses electrons (oxidation) while oxidizing agents such as oxygen or chlorides gain electrons. The rate and pattern of korroosion depend on the metal or alloy, the environment, temperature, and the presence of electrolytes and moisture.

Common modes include uniform corrosion, where material thins evenly; localized forms such as pitting and crevice corrosion; galvanic corrosion at interfaces between dissimilar metals; intergranular corrosion along grain boundaries; and stress corrosion cracking, where tensile stress and a corrosive medium promote crack growth. Microbiologically influenced korroosion can also occur in certain settings.

Environmental factors strongly influence korroosion. Water and oxygen are frequent reactants; chlorides, acids, and salts accelerate attack. Higher temperature, humidity, and stagnant fluids increase rates. Protective oxide films provide passivation for some alloys, but they can break down under aggressive environments or mechanical damage.

Prevention and control rely on material selection, protective coatings and barrier layers, and corrosion inhibitors. Cathodic protection (sacrificial anodes or impressed current) can reduce corrosion of pipelines and tanks. Design strategies, such as avoiding crevices, proper drainage, and controlling exposure, also reduce risk. Regular inspection and maintenance are essential.

Korroosion has substantial economic and safety implications across infrastructure, energy, transportation, and consumer devices. Rates are commonly expressed in units such as millimeters per year (mm/year) or mils per year, and monitoring uses weight loss measurements or electrochemical techniques to assess corrosion behavior and evaluate protective measures.