Electrocorrosion

Electrocorrosion is a phenomenon where electrical currents accelerate the corrosion of metallic materials. This typically occurs in environments where a metal is exposed to an electrolyte, such as water or soil, and an electrical potential difference exists. The electrical current can be generated from various sources, including stray currents from electrical equipment, grounding systems, or even galvanic effects between dissimilar metals.

When an electrical current flows through an electrolyte and interacts with a metal, it drives electrochemical reactions. At the anode, where the current enters the electrolyte from the metal, the metal atoms lose electrons and become positively charged ions, dissolving into the electrolyte. This process is essentially accelerated oxidation, leading to material degradation. At the cathode, where the current leaves the electrolyte and enters the metal, reduction reactions occur, which may or may not be directly damaging to the cathode itself, but the overall circuit facilitates the anodic corrosion.

The rate of electrocorrosion is dependent on several factors, including the current density, the conductivity of the electrolyte, the electrochemical properties of the metal, and the temperature. Common examples of electrocorrosion include the rapid deterioration of pipelines exposed to stray currents from electric railways or the corrosion of metal structures in contact with faulty electrical systems. Mitigation strategies often involve isolating the metal from the electrical source, using insulating materials, or implementing cathodic protection systems to make the metal structure the cathode in an electrochemical cell, thereby preventing it from corroding.