Preparing HNS/n-Al heat-resistant microspheres with enhanced combustion performance using droplet microfluidic technology

Reducing the formation of large carbon clusters during the combustion of energetic materials (EMs) and improving their comprehensive performance hold great significance. With fluororubber (F₂₆₀₄) as a binder, this study prepared HNS/n-Al microspheres with different n-Al contents (5%, 10%, and 15%) using droplet microfluidic technology. Then, it characterized and tested the morphology, particle size distribution, dispersibility, crystal structure, thermal properties, mechanical sensitivity, and combustion behavior of the microspheres. The results show that the prepared microspheres had regular shapes, uniform particle sizes, and excellent dispersibility and contained more homogeneous components than physically mixed samples. Furthermore, the microspheres retained the crystal structures of the raw materials, enjoying high safety performance. The thermal analysis shows that HNS/n-Al microspheres had high heat resistance (thermal decomposition temperature: over 354 °C) and that a higher n-Al content was associated with more thorough thermal decomposition reactions of HNS (HNS: 83%, HNS/n-Al: 84%, 86%, and 93%). The ignition experiments show that the HNS/n-Al microspheres possessed excellent and stable combustion performance, as evidenced by more complete combustion reactions and significantly elevated energy release efficiency. Therefore, it is expected to achieve high-energy and high-speed responses of carbon-rich EMs and promote their practical applications.