hapettumiskorroosio

Hapettumiskorroosio, also known as pitting corrosion, is a localized form of corrosion that results in small holes or pits in a metal surface. This type of corrosion is particularly dangerous because it can penetrate the metal rapidly, leading to failure even when the overall material loss is minimal. It typically occurs in environments containing aggressive ions, such as chlorides, which can break down the passive protective film that normally forms on many metals, like stainless steel.

The process of pitting corrosion usually begins with a localized breakdown of the passive layer. Once a small defect occurs, the exposed metal surface beneath it can become an anode, while the surrounding intact passive layer acts as the cathode. The presence of aggressive ions, particularly chloride ions, plays a crucial role in accelerating this process. These ions can migrate into the developing pit, creating a localized environment with a low pH and high concentration of metal ions. This acidic and corrosive microenvironment further promotes the dissolution of metal within the pit, causing it to deepen and widen.

Factors that influence hapettumiskorroosio include the type of metal, the concentration and type of corrosive ions present, temperature, and the surface condition of the metal. Stainless steels, for example, are susceptible to pitting in chloride-containing environments despite their inherent corrosion resistance. Detecting and preventing pitting corrosion is vital in many industrial applications, especially those involving harsh chemical environments, to ensure the integrity and safety of metal structures and components.