Synthesis of FeTi from mixed oxide precursors

Abstract

A study was carried out on the synthesis of FeTi intermetallics from mixed oxide precursors using the method of electro-deoxidation. Fe 2O 3 and TiO 2 mixed in molar proportions of 1:2 were sintered at temperatures ranging from 900 °C to 1300 °C. The sintered pellet of mixed oxides, connected as cathode, was then electrolyzed in a molten CaCl 2 at 900 °C using a graphite anode at a potential of 3.2 V. The electrolysis yielded the target composition FeTi in substantial amounts only when the sintering temperature was close to or above 1100 °C. The process of deoxidation was followed with the use of interrupted experiments. This has shown that the two-phase structure of Fe 2TiO 5 and TiO 2 in the oxide pellet reacts with the molten salt even before the electrolysis forming CaTiO 3, transforming the rest into a mixture of ilmenite (FeTiO 3) and a spinel phase (Fe 2TiO 4). During electrolysis these complex oxides were converted into simpler ones. Fe is the first element to be produced followed by the intermetallic Fe 2Ti. FeTi evolves quite late in the electrolysis which seemed to have followed the reduction of CaTiO 3. It is shown that interrupted experiments and examination of partially reduced pellets yield considerable information with regard to the sequence of changes that occur during the deoxidation process.