A study of salt-assisted solution combustion synthesis of magnesium aluminate and sintering behaviour

Abstract

We synthesized nano MgAl2O4 with a ~80 nm particle size by salt-assisted solution combustion synthesis using LiCl as salt. Nano MgAl2O4 produced by conventional solution combustion synthesis commonly exhibits poor uniformity in terms of size with partially sintered particles and a high degree of agglomeration, leading to poor sinterability. It was found in this study that the use of the salt-assisted solution combustion method has successfully lowers the degree of agglomeration with uniform particle size and morphology, demonstrating superior sinterability. Conventional sintering in air atmosphere at 1550 ℃ of MgAl2O4 obtained by salt-assisted solution combustion followed by calcination at 700–1100 ℃ yielded up to 94% of relative density, while the conventional solution combustion method could not match this. In addition, using the spark plasma sintering technique, fully dense (over 99%) submicrometer (~340 nm) transparent polycrystalline MgAl2O4 with elevated mechanical properties (~16.6 GPa) was achieved. The salt-assisted solution combustion method could be effectively used for fully dense material, but can be further developed for various nano oxide materials where high dispersion with a low degree of agglomeration is preferred.