Mechanism of zinc oxide–aluminum aluminothermic reaction

In this study, the aluminothermic reaction of a mixture of aluminum and zinc oxide powders ball milled at ambient temperature was investigated employing X-ray diffraction (XRD), differential thermal analysis (DTA), and electron microscopy (SEM) techniques. The kinetics of the reaction was studied based on DTA results to evaluate the mechanism and the activation energy of the reaction. The reaction mechanism was recognized to be an interface controlled one. The activation energy as well as the ignition temperature of the aluminothermic reaction was found to decrease significantly with increasing the milling time. The ignition temperature of the reaction was reduced from 1008 °C for the unmilled mixture to 563 °C for the mixture milled for 60 min. This was rationalized in terms of the microstructural changes observed in the milled mixtures. The activation energy also decreased from 848 kJ/mol for the unmilled mixture to 119 kJ/mol for the mixture milled for 60 min.