The effects of different precipitant agents on the formation of alumina-magnesia composite powders as the magnesium aluminate spinel precursor

Al2O3/MgO composite powders were synthesized via a partially wet chemical method. The effects of precipitant agent on the morphology, size and chemical composition of the resultant powders were investigated. The structures of rod-like with polygonal prism surface, platelet-like and uniform spherical Mg-compound particles were successfully prepared by using ammonium hydrogen carbonate, sodium hydroxide and ammonia water as precipitant agents, respectively. Analysis results proved that using ammonium hydrogen carbonate as precipitant agent produced nesquehonite (MgCO3 center dot 3H(2)O) Mg-compounds but in the case of other two precipitant agents, Mg-compound particles with magnesium hydroxide (Mg(OH)(2)) chemical composition were obtained. The morphological features of MgO particles in Al2O3/MgO composite powders were the same as individual Mg-compound particles. Furthermore, conversion of the Al2O3/Mg-compound precursor synthesized with ammonia water to pure magnesium aluminate spinel particles was studied. The precursor converted to pure magnesium aluminate spinel phase with 220 nm particle size at 1200 degrees C. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.