Enhancing the thermal reactivity of AP crystals by coating of Al-based bi-metal nanocomposites

•Core-shell structured AP@Al/TMs reactive composites have been prepared.•Al/Ni and Al/Co improved the heat release of thermal decomposition of AP by 84.8% and 42.1%, respectively.•The physical models for AP thermal decomposition reaction under the effect of Al/TMs have been proposed. A series of AP reactive composites modified by Al/TMs bi-metal compounds including Al/Ti, Al/Ni and Al/Co have been successfully prepared by acoustic resonance mixing. Various analysis techniques have been utilized and results indicate that the Al/Co exhibits the strongest thermal interaction effect on the thermal decomposition of ammonium perchlorate (AP) by merging reaction steps with enhanced thermal reactivity. In comparison to the pure AP, the peak temperatures of high temperature decomposition (HTD) of AP in the presence of Al/Ti, Al/Ni and Al/Co are significantly decreased by 60.3 °C, 76.9 °C and 100.2 °C, respectively. Moreover, the apparent activation energies obtained for AP@Al/Ti, AP@Al/Ni and AP@Al/Co composites are 96.5 kJ·mol−1, 103.5 kJ·mol−1 and 53.6 kJ·mol−1, respectively. The thermolysis physical models of AP in composites of AP@Al/Ti, AP@Al/Ni and AP@Al/Co appear to follow three-dimensional random nucleation and nucleus growth (A3), whereas the A3, chain scission and phase boundary-controlled reaction are found to be the most appropriate models to represent the three-step thermal decomposition of pure AP. Owing to the high thermal interaction activity, as great bi-metal fuels, Al/TMs can also be considered as outstanding additives for AP thermal decomposition.