Chemical synthesis and thermal evolution of MgAl2O4 spinel precursor prepared from industrial gibbsite and magnesia powder

A chemical route, using industrial raw materials, was developed for the synthesis of MgAl2O4 spinel precursor. The as-obtained powder was then calcined in air, up to 1200 °C for a period of 1 h. It was found that spinel single phase is formed at several hundred degrees lower than temperatures reported for the conventional powder preparation methods. Moreover, at 500 °C the degree of crystallinity is higher than that reported by other chemical processes at this temperature. The calcined powder reaches 83% of relative density at 1200 °C, indicating reactivity and good sintering behaviour. Scanning electron microscopy images revealed that the product consisted of fine spherical particles of magnesium aluminate spinel.