Thermodynamics, kinetics and mechanism analysis of aluminothermic reduction for preparing Al-Zr alloy

Abstract

In this study, we investigated the thermodynamics and kinetics of the aluminothermic reduction of ZrO2. The results of thermal analysis and isothermal heat treatment showed that the aluminothermic reduction of ZrO2 was an exothermic reaction that occurred at . 958.8°C. The aluminothermic reduction process does not produce metal Zr, but when the stoichiometric number of Al:ZrO2 was 13:3, Al3Zr and Al2O3 can be obtained by the reaction. The activation energy of the reaction was 1589.89 kJ/mol, and the reaction order was 1.90. The aluminothermic reduction process and mechanism of ZrO2 in the presence of potassium cryolite as the molten salt medium was also studied. The results showed that ZrO2 dissolved in potassium cryolite molten salt and participated in the reduction reaction in the form of Zr–O–F complex ions, while the by–product Al2O3 also dissolved in potassium cryolite to further promote the formation of the Al–Zr alloy.