Formation of Iron Oxides by Surface Oxidation of Iron PlateReportar como inadecuado

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Croatica Chemica Acta, Vol.85 No.1 April 2012. -

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

corrosion; α-Fe; hematite; magnetite; wüstite

Autor: Marijan Marciuš - ; Ruđer Bošković Institute, P. O. Box 180, HR-10002 Zagreb, Croatia Mira Ristić - ; Ruđer Bošković Inst



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