Different oxidation reactions of ilmenite induced by high energy ball milling

Oxidation reactions of ilmenite (FeTiO3) 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 degrees C) reaction with the formation of intermediate phases (Fe2Ti3O9 and Fe2O3) and high-temperature (>1000 degrees C) reactions with the formation of final thermally stable phases (Fe2TiO5 and TiO2). 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 Fe2TiO5 phase transforms to the metastable Fe2Ti3O9 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. (C) 1998 Elsevier Science S.A.