Survey on the Influence of Temperature and Holding Time on Synthesis of Hercynite by Molten Salt Method

Hercynite، FeAl2O4، was synthesized via molten salt synthesis method in the coke bed at 800°C with 3h of holding time. It was synthesized by reacting stoichiometric compositions of Al2O3 and FeCl2. 4H2O in eutectic compositions of alkaline chlorides NaCl-KCl-LiCl. The reactant to salt ratio was 1 to 3. The phase formation، and morphology of these synthesized powders after washing and filtration were characterized via X-ray diffraction (XRD)، and scanning electron microscopy (SEM). Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were performed at temperatures up to 1000 °C at a heating rate of 10 °C/min in argon atmosphere، to elucidate the different reaction mechanisms in the synthesis of Hercynite by the molten-salt method. The effects of processing parameters including the temperature and holding time on the formation of FeAl2O4 were investigated. The results demonstrated that the formation of FeAl2O4 spinel could be initiated at 700°C. By increasing the temperature to 900 °C and holding time، the amounts of FeAl2O4 particles in the resulting powder increased at the expense of Hematite and Al2O3. Morphology of the synthesized powder was cubic and tetragonal، increased by increasing the holding time and temperature.