korroosioa

Korroosioa, Basque for corrosion, refers to the deterioration of materials—most often metals—caused by chemical or electrochemical reactions with their environment. This process reduces strength, appearance and functionality, and can lead to leaks, failures or costly maintenance.

Most metal corrosion is electrochemical. In an electrolyte, metal atoms at exposed surfaces oxidize to form metal ions (anodic reaction), while electrons transfer to a cathodic site where reduction occurs, typically reducing oxygen or hydrogen ions. The rate and pattern depend on the metal, alloy, environment and microstructure. Common forms include uniform corrosion, where material degrades evenly; pitting and crevice corrosion in localized spots; galvanic corrosion when dissimilar metals are electrically connected; intergranular corrosion along grain boundaries; and stress-corrosion cracking in the presence of tensile stress.

Key factors are environmental conditions (water, oxygen, chlorides, pH, temperature), material properties (base metal, alloying elements, protective oxide layers) and exposure duration. Real-world examples include carbon steel in seawater, aluminum alloys in oxidizing media, and stainless steel in chloride-rich environments.

Prevention and control rely on design and material choice, protective coatings and paints, passivation and stabilizing oxide layers, cathodic protection (sacrificial anodes or impressed current), corrosion inhibitors, and regular inspection and maintenance. Proper selection aims to minimize crevices, avoid galvanic couples, and keep environments less aggressive.

Corrosion rates are often reported in units such as millimeters per year (mm/year) or mils per year, measured by weight loss, electrochemical impedance spectroscopy or other probes. Understanding korroosioa supports safer infrastructure, longer service life, and reduced maintenance costs.