Microstructure of Iron Dispersing Al2O3 Particle Reduced from (Fe,Al)2O3 by CO–CO2 Gaseous
Katsuhiko Takahashi, Masahiro Kawakami
Carbon monoxide reduction of (Fe,Al)2O3 was carried out in order to clarify the possibility for ODS to be made by selective reduction of solid solution. The microstructure of reduction product was observed with XRD, SEM and EDS. The results are summarized as follows.
The precipitate particle of about 100 nm was observed in iron reduced by 97%CO–3%CO2 at 1273–1373 K and was identified as κ′-Al2O3. On the other hand, the precipitate particle was Fe(Fe,Al)2O4 of spinel structure by using low reducing potential gas of 80%CO–20%CO2. The size of their particle was more than 200 nm.
And then, the sequential reduction of (Fe,Al)2O3 by various CO–CO2 ratios at 1273 K was carried out to investigate the structure transformation of products during CO reduction.
Solid solution of (Fe,Al)2O3 was reduced to solid solution of Fe3O4(FeOAl2O3). When the iron oxide was reduced to ‘FeO’, the Fe3O4(FeOAl2O3) was transformed to ‘FeO’ and Fe(Fe,Al)2O4 of spinel structure with the irregular shape. The solubility of Al2O3 in ‘FeO’ was less than 1%. It seemed that the size of Al2O3 particle in reduced iron depends on the that of Fe(Fe,Al)2O4 particle in FeO, which was affected by reducing potential.
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