Influences of metal ions on the formation of γ-FeOOH and magnetite rusts

To elucidate the role of anti-corroding alloying metals in weathering steels, the gamma-FeOOH and Fe3O4 particles were prepared by air-oxidation of FeSO4 solutions containing different amount of Ti(IV), Cr(III), Cu(II) and Ni(II). The crystallinity and particle size of gamma-FeOOH were lowered by adding Cr(III), Cu(II) and Ni(II) but not influenced by Ti(IV). All the metal ions impeded the crystallization and particle growth of Fe3O4 in a similar manner. The results on gamma-FeOOH and Fe3O4 were compared with those on alpha- and beta-FeOOHs previously reported to know the comprehensive effects of metal ions on the formation of rusts. (C) 2002 Elsevier Science Ltd. All rights reserved.