Elektrokorroision

Elektrokorrosion, also known as galvanic corrosion, is an electrochemical process that occurs when two dissimilar metals are in contact in the presence of an electrolyte. This situation creates a galvanic cell, similar to a battery, where one metal acts as the anode and the other as the cathode. The anode is the more chemically active metal and will corrode, while the cathode, the less active metal, will be protected.

The driving force behind elektrokorrosion is the difference in electrochemical potential between the two metals. When a conductive path is established between them, and an electrolyte (such as saltwater, moisture, or even acidic soil) is present, electrons flow from the anode to the cathode. This flow of electrons initiates the corrosion process at the anode, where metal atoms are oxidized and dissolve into the electrolyte.

The rate of elektrokorrosion depends on several factors, including the difference in electrochemical potential between the metals, the conductivity of the electrolyte, the surface area ratio of the anode to the cathode, and environmental conditions like temperature and pH. For example, connecting copper and steel in a humid environment will lead to rapid corrosion of the steel.

Common examples of elektrokorrosion include the corrosion of steel fasteners in aluminum structures, or the pitting of the inner surface of water heaters made of steel with copper piping. Mitigation strategies involve selecting metals with similar electrochemical potentials, using insulating materials to separate dissimilar metals, or applying protective coatings to the more susceptible metal. Sacrificial anodes, made of a more active metal, are also frequently used to protect a less active metal structure.