Influences of Metal Ions on Formation of α-FeOOH Rust

Single and Multiple Additions of Cu(II), Ni(II) and Ti(IV)

Abstract

To explore functions of unti-corroding alloying elements in weathering steels, α-FeOOH rust particles prepared from aqueous Fe(NO₃)₃ solutions added with Cu(II), Ni(II) and Ti(IV) of metal/Fe=0-0.1 in atomic ratio at 30, 50 and 100°C were characterized by various means. Most of the added metal ions were contained in the formed rust particles. Influences of the metal ions on the structure of formed α-FeOOH depended on kind of added metal ions and preparation temperature. The crystallinity of the products at 30°C examined by XRD was reduced by addition of all the metal ions in the order of Cu(II)>Ni(II)≈Ti(IV) and the product at Cu/Fe=0.1 was noncrystalline. The results of specific surface area showed that less crystalline products comprise agglomerates of fine particles. The simultaneous addition of Cu(II), Ni(II) and Ti (IV) exhibited no specific multiple or compensating effect, which indicates that these metal ions independently affect α-FeOOH formation.