Synthesis of hercynite under air atmosphere using MgAl2O4 spinel

Abstract

In this paper, the effect of MgO and MgAl2O4 spinel addition on the formation of hercynite phase was studied. For this reason, the stoichiometric mixtures of hematite and calcined alumina with various amounts of MgO were used. Moreover, the mixtures of hematite with various amounts of MgAl2O4 spinel were prepared. Afterwards, the compositions were fired at 1450 °C under air atmosphere and the phase composition and microstructure of fired samples were studied by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The results showed that MgO addition leads to formation of spinel, which has great effect on the formation of hercynite phase under air atmosphere. Spinel is formed along with hercynite in the composition with addition of MgO. Besides, the hercynite phase can be formed completely in the composition containing 60 wt.% spinel and 40 wt.% hematite.