Aluminum–Fluorine Composite Particles: Microstructure Optimization for Improved After-Burning Effect in Thermobaric Explosives

Aluminum nanopowder exhibits a limited degree of reactivity during the after-burning stage of thermobaric explosives due to factors such as sintering during combustion, which diminishes the destructive performance of these explosives. This paper employs the solvent/nonsolvent method to prepare aluminum–fluoride composites with three different microstructures (activities), replacing traditional aluminum powder in thermobaric explosives. Three formulations─HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)-based thermobaric explosives (HMX-TE-1, HMX-TE-2, and HMX-TE-3)─were developed, with increasing contact areas between the aluminum powder and fluoropolymer. Confined explosion tests revealed that HMX-TE-3 maintained higher mean quasi-static pressure over 500 ms and exhibited a temperature exceeding 1650 K for 2.03 ms─significantly longer than other samples. The HMX-TE-2 (188.0 kPa·s–1) and the HMX-TE-3 (179.9 kPa·s–1) samples have significantly smaller pressure reduction rates at 50 ms than the HMX-TE-1 sample. Calculations based on explosion fireball temperatures indicated enhanced aluminum powder reactivity, increasing from 0.62 for HMX-TE-1 to 0.87 and 0.96 for HMX-TE-2 and HMX-TE-3, respectively. Additionally, RMD simulations were conducted to verify the impact of the microstructure on the combustion performance of aluminum powder.