rdza

Rdza, or rust, is the corrosion product formed when iron or steel oxidizes in the presence of water and oxygen. It typically appears as a reddish-brown, flaky layer on the surface. Rust consists mainly of hydrated iron oxides and iron hydroxides, and it weakens steel by altering its surface structure.

Rust forms through electrochemical reactions that occur at the metal’s surface. Iron loses electrons (oxidation) at anodic sites, while oxygen is reduced at cathodic sites, with water acting as an electrolyte that facilitates ion transport. The process is accelerated by moisture, salts, acids, and temperature fluctuations. The resulting rust is usually porous and non-protective, allowing continued penetration of water and oxygen.

Rust mainly affects iron and steel. Other metals form different oxides and patinas; for example, copper develops a green patina rather than rust. The rate of rusting depends on environmental factors such as humidity, salinity, temperature, and the presence of protective coatings or contaminants. Typical rust is reddish to brown and forms uneven, flaky layers that can trap moisture and debris.

The impact of rust on structures and machinery can be significant. It reduces material thickness, weakens joints, and increases maintenance costs. If rust progresses unchecked, it can lead to structural failure. Protective coatings, galvanization, and the use of corrosion-resistant alloys help slow or prevent rust by isolating iron from moisture and oxygen.

Prevention and control strategies include applying paints or sealants, using zinc coatings (galvanization), employing stainless steels with chromium to form a passive oxide layer, implementing cathodic protection, and controlling environmental conditions such as humidity and salt exposure. Regular inspection and maintenance are important for early detection and remediation.