Corrosion is the wastage of material by the chemical action of its environment. It does not include mechanisms such as erosion or wear, which are mechanical. Aqueous corrosion is the oxidation of a metal via an electrochemical reaction within water and its dissolved compounds. Aqueous corrosion is dependent on the presence of water to act as an ion conducting electrolyte.
An understanding of aqueous corrosion is essential for all industries. The lifetime and safety of chemical plants, offshore platforms and ships are all dependent on controlling and predicting corrosion rates and products.
This TLP introduces the concepts of electrochemical equilibrium reactions, electrode potentials, construction of Pourbaix diagrams using the Nerst equation and their interpretation. A Pourbaix diagram is a plot of the equilibrium potential of electrochemical reactions against pH. It shows how corrosion mechanisms can be examined as a function of factors such as pH, temperature and the concentrations of reacting species.