The formation of Mg ferrite by mechanical alloying and sintering

The kinetics of Mg-ferrite formation during ball milling of iron and magnesium oxides powder have been examined. A mixture of Fe2O3 and MgO powders corresponding to nominal composition of one mole each, was subjected to milling, using a stainless steel ball mill. The weight ratio between the steel balls and the powders was approximately 8:1. Powders, after different milling times, were examined by X-ray diffractometry and optical microscopy. For the mill-operating condition investigated, the particle sizes in the mill generally decreased with milling time, indicating a greater tendency for particle fracture than agglomeration (welding). After a milling time of 23 h, Mg-ferrite was formed. The milled powders were sintered for 2 h at temperatures of 800, 1000, and 1300 degrees C. For comparison, unmilled powders were also sintered at the same temperatures and time. Complete formation of Mg-ferrite was obtained only after milling followed by sintering at 1300 degrees C for 2 h, while unmilled particles showed partial formation of Mg-ferrite when sintered at the same temperature for the same time. (C) 1998 Elsevier Science B.V.