The Effect of Al Particles Size on the Thermal Behavior and Kinetics of Al‐MnO₂ Thermite System

Abstract

Micron-MnO2 powder has unique thermal decomposition process compared with other metal oxides, and the different characteristics of components in thermite could affect the thermal performance of the whole system directly. In this work, the Al powder with different three particle sizes was combined with micron-MnO2 to prepare the Al-MnO2 thermite system, and the effect of Al powder particle sizes on the whole thermal behavior was studied. Firstly, the thermal decomposition process of micron-MnO2 and purity of Al powder are tested by TG-DSC. By using ultrasonic dispersion method, the fuel-rich thermite samples were prepared and characterized by SEM and TG-DSC at different heating rates. The Kissinger method was also employed to calculate the activation energy for the first exothermic peak. It was found that the thermal decomposition process of MnO2 in the thermite system can be significantly disturbed by different Al particles size. In other words, the effect of Al particle sizes on the thermite can be magnified due to the unique decomposition properties of micron-MnO2 instead of onset temperature of exothermic reaction changing simply. The activation energy of thermite system decreased with the reduction of Al particle sizes in micron-level, while in nanolevel the activation energy markedly increased. Finally, the possible reasons for phenomenon were discussed.

α-MnO2 Nanowire Structure Obtained at Low Temperature with Aspects in Environmental Remediation and Sustainable Energy Applications

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Changes in the state of matter of KCIO4 to improve thermal and combustion properties of Al/MoO3 nanothermite

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“…This finding led to our exploration of metal oxides that are capable of harnessing the energy density of nAl while being microwave sensitive. The manganese dioxide (MnO 2 ) reaction with nAl has been previously studied − and the theoretical heat release from the thermite reaction of MnO 2 and Al is higher or comparable to classical thermites of Al/Fe 3 O 4 and Al/CuO . Moreover, multivalent manganese oxides (−3 to +7 oxidation states) have been shown to have high dielectric constant values and have been utilized in microwave-assisted catalysis applications. − The dielectric properties of the oxidizer open avenues for exploration of the metal oxide in nAl-based microwave-stimulated thermites.…”