The combustion reactivity of core-shell Al/Fluoropolymers and application in RDX-based explosives

Aluminum (Al) powder is widely applied in thermobaric explosives due to its high energy density and favorable reaction kinetics. However, the inert oxide layer (Al₂O₃) on Al particles limits combustion reactivity and energy efficiency. Fluoride-based surface modification has been developed as an effective approach to address this issue. Here, four classical fluoropolymers (F11, F14, PVDF, PTFE) are employed as coatings to prepare core-shell Al/Fluoropolymer. The combustion experimental results demonstrate that the core-shell Al/PTFE exhibits the highest flame propagation rate (52.88 mm·ms⁻¹) and pressure output (109.02 kPa) performance. Consequently, core-shell Al/PTFE is selected as a high-energy fuel to prepare RDX/Al/PTFE microspheres via the emulsion and solvent evaporation method, which can enhance the energy performance of RDX. The effects of the core-shell Al/PTFE ratio and RDX content on the combustion heat and pressure output are systematically investigated. The peak pressure reaches a maximum of 187.8 kPa when the mass ratio of RDX, Al, and PTFE is 60: 25: 10. Additionally, RDX/Al/PTFE microspheres exhibit significantly higher laser-induced air shock velocities, detonation heat, and detonation pressure than those of pure RDX and RDX/Al. The mechanism underlying the enhanced reactivity and energetic performance is attributed to the ability of PTFE to etch the inert Al₂O₃ shell on the surface of Al particles, thereby improving post-combustion reactions and significantly increasing the overall energy output of RDX explosives. This work offers a novel design strategy for high-energy structural thermobaric explosives for the practical applications.