Fe-O-Sn (Iron-Oxygen-Tin)
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Section II: Phase Diagram Evaluations
Fe-O-Sn (Iron-Oxygen-Tin) The early results on this ternary system were reviewed by [1989Rag], who presented two isothermal sections at 800 and 475 °C from the studies of [1984Pan] and [1974Moh], respectively, with emphasis on the metal-rich region. Recently, [2004Han], during their investigations of the Fe-O-Sn-Zn quaternary system, determined the phase equilibria along the Fe2O3-SnO2 join.
Temperature, °C
V. Raghavan
Binary Systems The Fe-O phase diagram [1991Wri] exhibits the following compounds. Wustite (FeO) is a metal-deficient monoxide with the B1, NaCl-type cubic structure. Magnetite (Fe3O4) has the H11, Al2MgO4-type cubic structure. Hematite (aFe2O3) is D51-type rhombohedral. Other less-common polymorphic forms of the above compounds are known [1991Wri]. The Sn-O system [1974Moh] depicts three intermediate phases: SnO (tetragonal and orthorhombic forms, stable below 270 °C), Sn3O4 (triclinic; stable below 450 °C) and SnO2 (Cassiterite; C4, rutile(TiO2)-type tetragonal).
Ternary Phase Equilibria With starting powders of Fe2O3 and SnO2 (99.5+% purity), [2004Han] prepared pellets of powder mixtures and annealed them in air between 1400 and 1100 °C for 48-97 h, which were then cooled in air. The microstructures were examined with optical and scanning electron microscopy. The phase compositions were measured with electron probe microanalyzer. The projection of the phase boundaries on to the Fe2O3-SnO2 join determined by [2004Han] is shown in Fig. 1. The new results, which show some disagreement with those found by [1966Cas], are to be preferred in view of the direct measurement of the phase compositions by electron probe microanalysis.
372
' Fe O '
SnO 2
2 3
Mole Percent SnO 2
Fig. 1 Fe-O-Sn projection of phase equilibria in air on to the Fe2O3-SnO2 join [2004Han]
References 1966Cas: J. Cassedanne, The aFe2O3-SnO2 Phase Diagram, Ann. Acad. Bras. Cienc., 1966, 38(2), p 265-267, in French 1974Moh: G.H. Moh, Tin Containing Mineral Systems. Part I: The Sn-Fe-S-O System and Mineral Assemblages in Ores, Chem. U Erde, 1974, 33, p 243-275 1984Pan: Z. Panek and K. Fitzner, Gibbs Energy of Formation of Solid Tin-Iron-Oxide (SnFe2O4), Thermochim. Acta, 1984, 78(1-3), p 261-267 1989Rag: V. Raghavan, The Fe-O-Sn (Iron-Oxygen-Tin) System, Phase Diagrams of Ternary Iron Alloys, Part 5: Ternary Systems Containing Iron and Oxygen, Indian Institute of Metals, Calcutta, 1989, p 282-288 1991Wri: H.A. Wriedt, The Fe-O (Iron-Oxygen) System, J. Phase Equilib., 1991, 12(2), p 170-200 2004Han: R. Hansson, P.C. Hayes, and E. Jak, Experimental Study of Phase Equilibria in the Fe-Sn-Zn-O System in Air, Can. Metall. Q., 2004, 43(4), p 545-554
Journal of Phase Equilibria and Diffusion Vol. 31 No. 4 2010
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