Original scientific paper

https://doi.org/10.5562/cca1943

Formation of Iron Oxides by Surface Oxidation of Iron Plate

Marijan Marciuš orcid.org/0000-0002-4747-5981 ; Ruđer Bošković Institute, P. O. Box 180, HR-10002 Zagreb, Croatia
Mira Ristić orcid.org/0000-0003-0033-9840 ; Ruđer Bošković Institute, P. O. Box 180, HR-10002 Zagreb, Croatia
Mile Ivanda ; Ruđer Bošković Institute, P. O. Box 180, HR-10002 Zagreb, Croatia
Svetozar Musić ; Ruđer Bošković Institute, P. O. Box 180, HR-10002 Zagreb, Croatia

Abstract

Oxidation of iron plates (α-phase) at high temperatures and in atmospheric conditions was monitored. The composition of oxidation products was analyzed with XRD, Raman and Mössbauer spectros-copies, whereas the morphologies of oxidation products were inspected by FE-SEM. The oxidation products formed at 300 and 400 °C consisted dominantly of magnetite and small fractions of hematite, whereas at 500 and 600 °C hematite was the dominant phase, as shown by XRD. In all these samples Raman spectra showed the presence of hematite in the outer oxidation layer. FE-SEM analysis showed the formation of nanowires at 500 °C and vertically grown hematite spikes against the lower oxidation layers at 600 °C. Oxidation products formed at 800 °C consisted of wüstite (Fe1–xO) as the dominant phase, nonstoichiometric magnetite (Fe3–xO4) and hematite (α-Fe2O3) in small fractions. The surface of these oxidation layers showed a hierarchical microstructure, as well as the hexagonal hematite rods vertically grown against the lower oxidation layers. The formation of the oxidation products can be considered a process which includes the oxidation of α-Fe to Fe1–xO and its transformation to Fe3–xO4 that further transforms to α-Fe2O3, probably via a short-lived γ-Fe2O3 (maghemite) phase. (doi: 10.5562/cca1943)

Keywords

corrosion; α-Fe; hematite; magnetite; wüstite

Hrčak ID:

80449

URI

https://hrcak.srce.hr/80449

Publication date:

30.4.2012.

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