High-quality and homogeneous HMX-based aluminized explosives using droplet microfluidic technology

The aggregation of nano-aluminum powder seriously hinders the energy release of aluminized explosives. This study developed a strategy of using the droplet microfluidic technology to prepare HMX/15 ​wt% n-Al/2 ​wt% (NC and F2604) high-energy microspheres and systematically studied the effects of different binders on the morphology (i.e., roundness) and dispersion properties of microspheres. Moreover, it investigated the thermal decomposition, mechanical sensitivity, and combustion performance using TG, differential scanning calorimetry (DSC), and mechanical sensitivity and combustion experiments. Results show that all the prepared microspheres are regular spherical and enjoy excellent dispersion and high packing density. Using NC as a binder offers more advantages, including favorable roundness, angle of repose, and bulk density values, which were found to be 0.921, 27.1°, and 0.723 ​g·cm^-3, respectively. Using fluorine rubber (F2604) as a binder promotes the oxidation of nano-aluminum and delays the decomposition of HMX. Meanwhile, the microsphere structure can effectively reduce the sensitivity, and the use of F2604 as a binder can significantly improve the safety performance. As a result, the obtained aluminum-containing explosives have impact and friction sensitivities of 60 ​J and 220 ​N, respectively. In addition, compared to physically mixed samples, the microsphere samples have significantly improved combustion performance, more intense combustion reactions, and a shorter burning time, all of which are attributed to their uniform structures and the interactions between components. These results indicate that the strategy using the droplet microfluidic technology provides a new method for preparing high quality aluminized explosives efficiently and safely.