Phase Transformations in Chemically Precipitated Mixtures for Alumomagnesium Spinel

The hydroxide precipitation method was used to produce initial materials for subsequent synthesis of magnesium aluminate spinel. Using IR spectroscopy and X-ray phase analysis methods, the processes of interaction between the materials obtained, phase transformations, and structural formation in Al spinel under thermal treatment was investigated. It was established that the spinel formation process passes via an intermediate phase, i.e., crystal hydrate Mg5Al4O11.15H2O, which in heat treatment transforms into magnesium aluminate spinel. With increasing temperature its structure is perfected and its quantity increases significantly. The formation of this phase ends at a temperature of 1300-1350 C. 8 refs.