Pittingkorroosioon

Pittingkorrosioon, also known as pitting corrosion, is a localized form of corrosion that leads to the formation of small holes or pits in a metal surface. This type of corrosion is particularly insidious because it can cause significant damage with a relatively small amount of metal loss, often going unnoticed until it reaches a critical stage. It typically occurs in environments containing aggressive ions, such as chlorides, which can break down the passive film that normally protects many metals.

The mechanism behind pitting corrosion involves a localized breakdown of the protective oxide layer. Once a small area is compromised, it becomes an anode, while the surrounding intact surface acts as the cathode. An electrochemical cell is established, with the pit acting as a continuous anode. The presence of aggressive ions like chloride ions is crucial, as they can facilitate the dissolution of metal ions within the pit and prevent the repassivation of the exposed surface.

Pitting corrosion can occur on a wide range of metals, but it is especially prevalent in stainless steels, aluminum alloys, and nickel alloys, which are often chosen for their corrosion resistance. Factors that influence pitting corrosion include the concentration of aggressive ions, temperature, pH of the environment, and the presence of crevices or surface defects that can concentrate corrosive species. Early detection and prevention are key to mitigating the damaging effects of pitting corrosion, which can compromise the structural integrity and performance of metal components.