Preparation of MgAl₂O₄ Spinel Powders via Freeze‐Drying of Alkoxide Precursors

Abstract

High-sinterability MgAI2O4 powder has been produced from alkoxide precursors via a freeze-drying method. Clear alumina sol and magnesium methoxide were used as starting materials in the process. The spinel powders were characterized by various techiques, such as thermal analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The tap density and sinterability of the spinel power are affected by the ballmilling techniques. Highly dense, transpiarent, polycrystalline MgA1204 has been obtained from these powders by sintering and hot isostatic pressing. Bimodal grain-size microstructure is observed in a HIPed sample. [

Influence of nano boehmite on solid state reaction of alumina and magnesia

“…Over the last few decades, numerous techniques have been used to prepare high purity magnesium aluminate spinel powder including solid-state synthesis hydrothermal synthesis [14], co-precipitation [15][16][17], microemulsion technique [18], microwave-assisted combustion processing [19], plasma spray decomposition [20,21], sol-gel of double or semi-alkoxides [22][23][24], the citrate-nitrate route [25,26], organic gel-assisted citrate process [27], aerosol method [28], freeze drying [29], decomposition of organometallic compounds [30][31][32][33], mechaniochemical synthesis [34,35], mechanical activation [1] and others [36][37][38]. Among them solid-state synthesis is the most common rout to produce commercial MA spinel.…”

Carbon dioxide reforming of methane by solid state synthesis supported catalysts

“…Other techniques have been developed for preparing oxide support. They include co-precipitation [16,18], solegel synthesis [25,26], hydrothermal synthesis [27] and freeze-drying [28].…”

Optical properties of nanocrystalline magnesium aluminate spinel synthesized from industrial wastes

“…The preparation of magnesium aluminate powders with high purity, chemical homogeneity, control of stoichiometry, fine particle size, narrow particle size distribution, and minimum particle agglomeration with high sinter activity has received considerable attention in order to improve the material properties [21]. Numerous wet chemical methods have been employed to synthesize magnesium aluminate fine particles, including solegel [22,23], co-precipitation [24e26], hydrothermal [27,28], microwave-assisted combustion processing [29], microemulsion [30], metal-organic processing [31e34], spray drying [35], freeze drying [36], and mechanochemical synthesis [37,38] techniques. The chemical co-precipitation method [39e42] ensures proper distribution of various metal ions resulting into stoichiometric and smaller particle sized product compared to some of the others.…”