FrettingKorrosion

Fretting corrosion is a surface degradation phenomenon that occurs when two surfaces in contact experience small, repetitive relative motions. This movement, often referred to as fretting or fretting wear, causes repeated displacements between the contacting asperities (microscopic high points) of the surfaces. The process typically takes place in environments with the presence of oxygen or other corrosive species.

The initial stage of fretting corrosion involves mechanical wear. The continuous rubbing action breaks down protective surface layers and generates fine wear debris. In the presence of oxygen, this debris oxidizes, forming hard, abrasive particles such as metal oxides. These oxidized particles are then trapped between the sliding surfaces, exacerbating the wear process and leading to increased material removal.

The corrosive aspect of fretting corrosion arises from the interaction of the wear debris and the surrounding environment. The newly exposed metal surfaces are more susceptible to chemical attack. If moisture and corrosive agents are present, electrochemical reactions can occur, leading to pitting and further material degradation. The cycle of mechanical abrasion and chemical corrosion reinforces each other.

Fretting corrosion can lead to a significant reduction in the fatigue life of components, particularly in applications involving vibration or cyclic loading. It is commonly observed in bolted joints, electrical connectors, and bearings where relative motion is unavoidable. Mitigation strategies often involve reducing the relative motion, using lubricants, applying protective coatings, or selecting materials with higher resistance to wear and corrosion.