Different oxidation reactions of ilmenite induced by high energy ball milling

Oxidation reactions of ilmenite (FeTiO 3 ) have been investigated during thermal annealing and ball milling processes using X-ray diffraction and thermal analyses. Thermal oxidation reactions consist of a low-temperature ( < 1000°C) reaction with the formation of intermediate phases (Fe 2 Ti 3 O 9 and Fe 2 O 3 ) and high-temperature ( > 1000°C) reactions with the formation of final thermally stable phases (Fe 2 TiO 5 and TiO 2 ). Only the low-temperature reaction occurred during ball milling at room temperature and the high-temperature reactions were not observed, even after a prolonged milling. It is also found that the thermally stable Fe 2 TiO 5 phase transforms to the metastable Fe 2 Ti 3 O 9 phase during milling in oxygen. The different behaviours of the oxidation of ilmenite between thermal annealing and mechanical milling are due to different structural stabilities of oxides and different reaction mechanisms.