Corrosion is the spontaneous oxidation of metals. It is an electrochemical process in which electrical phenomena and chemical reactions occur. This is also referred to as galvanic corrosion; different materials that have electrical contact and are both in an electrically conductive medium, such as soil or water. In this case, the different metals become electrodes and form a galvanic cell in interaction with each other and their environment. The two electrochemical partial reactions in a galvanic cell are:
– Metal oxidation at the anode where electrons are released
– Reduction (for example on oxygen) to the cathode where electrons are taken from
The oxidation takes place on the most base metal and the reduction on the most noble metal, corroding the least noble metal. The corrosion process can be accelerated in a salty and humid environment and even protective coatings can not fully protect metal objects in many environments.