Architecting nano-Al/HMX/CuO energetic micro-units unlocks superior interface and highly efficient combustion

Abstract

The combustion performance and interfacial-mechanical properties of the Al/HMX composite are pivotal to its application in propellant and explosive formulations. Although nano-aluminum (n-Al) possesses high reactivity, issues such as particle agglomeration and surface oxidation limit its combustion efficiency and mechanical properties, hindering its direct application. Spherical Al/HMX/CuO composite energetic micro-units were designed using multiscale simulations combining molecular dynamics and computational fluid dynamics. Using fluororubber F₂₆₀₃ as the binder, the micro-units were precisely and controllably fabricated employing coaxial microfluidic technology. Characterization indicates that the n-Al particles are pre-dispersed within the micro-units, suppressing their agglomeration. The addition of F₂₆₀₃ as an interfacial modifier enhances hydrophobicity and delays n-Al oxidation. The spherical morphology improves dispersion and flame propagation, while the encapsulation structure promotes efficient mass and heat transfer between n-Al and HMX, significantly enhancing combustion. In the optimized formulation with an Al/HMX mass ratio of 1:2 and 2% CuO content, the micro-unit exhibited a 100% increase in combustion rate, a stable heating rate of 1.04 × 10⁴ K s^–1, and a 5.5% rise in combustion temperature, outperforming physically mixed samples. By revealing the combustion mechanism and structure–performance relationship of energetic micro-units, this study demonstrates precision fabrication advantages of microfluidics to support designing high-performance energetic composites.