High-Energy Composite Fuels with Improved Combustion Efficiency by Using AlH₃ Embedded with Al Particles

Aluminum hydride (AlH₃) has attracted much attention due to its potential to replace aluminum (Al) as a novel energetic material in solid propellants. In this research, ammonium perchlorate (AP) and perfluoropolyether (PFPE) as functionalized coatings and a combination of acoustic resonance and spray drying technology have been employed to prepare AlH₃@Al@AP (AHAPs) and AlH₃@Al@AP@PFPE (AHAPs-F) energetic composite particles. The formulations of composite propellants and modified AlH₃ particles were designed and fabricated. Their thermal reactivity, reaction heat, density, vacuum stability, combustion performance, and condensed combustion products (CCPs) have been systematically investigated. The results show that the solid propellants containing AHAPs (SP13) and AHAPs-F (SP14) composites can significantly enhance the reactivity and energy output compared to conventional solid propellants with the mechanical mixture Al/AlH₃ (SP12). In particular, the total heat releases of SP13 and SP14 are almost 1.2 and 1.7 times higher than those of conventional ones (SP12, 1442 J g^-1), respectively. Among the AlH₃-based propellants, SP14 propellants exhibit the highest reaction heat of 5887 J g^-1, the most intensive flame radiation of 31.4 × 10³, and the highest combustion wave temperature of 2495 °C. Moreover, the particle size distribution of CCPs from SP14 propellants is much narrower and smaller than that of SP12, resulting in higher combustion efficiency.