Study on Thermal Chemical Reaction of Al/MnO2 Thermite

Abstract

To explore the reaction characteristics and mechanism of Al/MnO2 thermite, selecting the high purity micron grade Al and MnO2 powder, the Al/MnO2 thermite sample was mixed by the ultrasonic dispersion method. On the basis of the study of thermal decomposition of MnO2 powder, the thermal performance of the sample was study by simultaneous thermal analysis technique at the temperature range from room temperature to 900°C, and the reaction products were analyzed by X-ray diffraction (XRD). The microstructure changes of the thermite during reaction were observed by field emission scanning electron microscope (FE-SEM). The results showed that the MnO2 has two processes of thermal decomposition during the temperature rising, and the reaction products were Mn2O3 and Mn3O4, and the onset temperature were 498.3°C and 781.5°C, the heat release were - 197.1J/g and -57.4 J/g, respectively. Al/MnO2 thermite reaction contained a variety of chemical reactions, including two thermal decompositions and thermite reactions. The Al powder melted at 648.9°C. The thermite reaction was started at 547.8°C, and the peak temperature was at about 590.3°C. The measured heat release was 323.9 J/g. Thermite reaction process coincides with the first thermal decomposition of MnO2. And the heat release of thermite reaction completely covered the endothermic decomposition.