Combustion behaviour and reaction kinetics of GO/Al/oxidizing salts ternary nanothermites

Following recent developments in micro-scale energy systems, such as microthruster and igniters among others, there is now considerable interest in using tertiary nanothermites to meet the increasing demand in high energy density propulsion systems. The first objective of this research is to compare and analyze the thermal behaviour of different nanothermite tertiary compositions based on nano-aluminium (n-Al), graphene oxide (GO), various salt and metallic oxidizers. The second objective is to identify the thermite reaction mechanism through correlations with the activation energy and exothermic peaks. Thermogravimetry analysis coupled with a differential scanning calorimeter (TGA/DSC) was employed to elucidate the reaction process of these nanothermite compositions, while bomb calorimetry was used to measure their heat of combustion. The apparent kinetics parameters were calculated using Kissinger and Ozawa approaches. The results demonstrate that the addition of GO enhances the reactivity of nanothermites with both salt and metallic oxidizers by reducing the reaction onset temperature, activation energy and increasing the heat release. For nanothermites with oxidizing salts, the heterogeneous solid–gas reaction mechanism plays a more important role than the condensed phase reactions. In general, nanothermites based on oxidizing salts are more reactive than those with metallic ones, as indicated in both theoretical and experimental data. Among them, the GO/Al/KClO 4 nanothermite exhibits the highest heat release (9614 J g −1 ), while the GO/Al/K 2 S 2 O 8 nanothermite shows the lowest onset temperature and activation energy (380 °C and 105 kJ mol −1 ). This study provides benchmark information for optimizing the tertiary nanothermites design, use, storage and handling.