Formation of magnetite rust particles by reacting iron powder with artificial α-, β- and γ-FeOOH in aqueous media

To simulate the atmospheric corrosion of steels, magnetite (Fe3O4) rust particles were prepared in aqueous media containing iron powder (α-Fe) and artificial α-, β- and γ-FeOOH particles at pH = 6.0 and 50 °C for 24 h. The Fe3O4 formation was not recognized by treating the iron powder with α-FeOOH. When the iron powder treated with β- and γ-FeOOH, these materials were dissolved to generate Fe3O4 and α-FeOOH particles. The amount of formed Fe3O4 particles was in the order of β-FeOOH > γ-FeOOH ≫ α-FeOOH, which was strongly related to the density and solubility of FeOOH.