From sub-microsized MgAl2O4 powder to MgAl2O4-Si3N4 nanocomposite powder by spray drying of ultrasonicated suspensions

The prime objective of this work is an investigation on the effect of ultrasonic processing and suspension formulation including the amount of the binder and the dispersant agent on the morphology, circularity factor, and flowability of the resulting granules. In order to do so, the MgAl2O4−2.5‌vol%Si3N4 suspension was firstly prepared with ultrasonic irradiation of MgAl2O4-Si3N4 nanoparticles in distilled water with the assistance of a dispersant agent (Dolapix CE 64) and PVA (poly vinyl alcohol) binder. Then, the nanocomposite granules were produced by spray drying of the suspension. The characterizations of the initial powders and the obtained granules were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) analyses. The results showed that the ultrasonic treatment can break the initial agglomerated spinel powders into a fine distribution of particle size. Also, spray drying of the ultrasonic-treated suspension can produce granules with desirable morphology and flowability.