Revised pourbaix diagrams for iron at 25–300 °C

The Pourbaix diagrams, potential pH diagrams, for iron at 25–300 °C have been revised. The selection of thermochemical data has taken into account the experimental solubility of magnetite at T = 100–300 °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)2(cr), at 10−6m and T ≤ 85 °C, implying that the Schikorr reaction is not thermodynamically possible above this temperature. A corrosion region between iron and magnetite exists at all temperatures in high purity water (10∞ m), due to the hydrolysis products of iron(II).