Synthesis and characterization of nano MgAl2O4 spinel by the co-precipitated method

Magnesium aluminate (MgAl2O4) spinel powders were prepared by co-precipitation of stoichiometric amounts of magnesium and aluminum chlorides at 80 degrees C. Some sintering aids such as ZnO and MnO2 were added in the form of chlorides during the precipitation to study their effect on densification. The co-precipitated materials were a mixture of Mg-Al double hydroxide with the presence of few amounts of gibbsite and brucite. After heat-treatment of the precipitated powders up to 1000 degrees C, a crystalline spinel powder was obtained. The presence of 0.5, 1, 2 and 3 wt.% of ZnO or MnO2 as sintering aids increased sinterability after firing up to 1550 degrees C. The highest density was obtained for the samples containing 2 wt.% ZnO or 3 wt.% MnO2 which reached about > 94 and 96% theoretical density (TD), respectively. The mechanical properties increased by adding ZnO or MnO2, an exception being the sample containing 0.5 wt.% of ZnO for which relatively smaller value were obtained. (C) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.