Revised Pourbaix diagrams for iron at 25-300 deg C

The Pourbaix diagrams, potential pH diagrams, for iron at 25-300 deg C have been revised. The selection of thermochemical data has taken into account the experimental solubility of magnetite at T=100-300 deg C. Temperature extrapolations of thermochemical data for aqueous species have been performed with the revised Helgeson-Kirkham-Flower model, which also allows uncharged aqueous complexes to be handled. The Pourbaix diagrams show a stability region for ferrous hydroxide, Fe(OH) sub 2 (cr), at 10 exp -6 m and T < =85 deg C, implying that the Schikorr reaction is not thermodynamically possible above this temperature. A corrosion region between iron and magnetite exists at all temperature in high purity water (10 exp -8 m), due to the hydrolysis products of iron(II).