Corrosion

Corrosion is a natural aging process which occurs under the impact of atmospheric oxygen and water. In nature iron can only be found in a stable form as iron ore or iron oxide. In the production of iron in the blast-furnace process, iron ore is reduced to iron by adding carbon because oxygen has a higher affinity for carbon than for iron. This “reduced” state is thermodynamically instable, in other words the iron attempts to return to its energetically more stable state as iron oxide, i.e. to oxidise.

Corrosion is metal-specific, i.e. it depends on the composition of the metal and its surface texture. Consequently, to achieve effective corrosion protection it is necessary to match the protective mechanism to the metal to be protected.