Spaltkorrosion

Spaltkorrosion is a localized form of corrosion that occurs in the narrow gaps or crevices between two or more adjacent materials, or within a single material. This restricted geometry prevents free access of oxygen and can trap corrosive electrolytes.

The mechanism of spaltkorrosion is driven by differences in the concentration of dissolved oxygen within the crevice compared to the external environment. The area with higher oxygen concentration, typically outside the crevice, acts as the cathode, while the area with lower oxygen concentration inside the crevice acts as the anode, where metal dissolution occurs.

The electrolyte within the crevice can become acidified due to the electrochemical reactions. Metal ions released at the anode hydrolyze, releasing hydrogen ions and lowering the pH. This acidic environment further accelerates the corrosion rate within the crevice.

Common environments where spaltkorrosion is observed include marine atmospheres, industrial settings with chemical exposure, and even in domestic plumbing systems. Materials susceptible to spaltkorrosion include many metals and alloys, particularly stainless steels and aluminum alloys.

Preventive measures for spaltkorrosion involve eliminating or reducing the formation of crevices, such as by using continuous welds instead of intermittent ones, or by applying protective coatings to seal potential gaps. Proper material selection and maintaining a clean surface can also help mitigate the risk of spaltkorrosion.