Simple and controllable preparation of high-energy insensitive CL-20/DAAF composite microspheres with enhanced combustion and mechanical properties

High energy and low sensitivity are generally mutually exclusive in energetic materials, and precise regulation of the microstructure is an effective strategy to balance these properties. In this study, CL-20/DAAF composite microspheres with various microstructures—including core-shell, hollow, porous, and irregular hollow structures—were fabricated using a tubular continuous-flow device combined with the principles of phase separation and recrystallization. The influence of the binder on the morphology and properties was also investigated. The results demonstrated that, compared with raw CL-20, the composite microspheres exhibited significantly reduced sensitivity and improved mechanical properties. Specifically, the impact energy increased from 1.75 J to 7.50 J, and the friction sensitivity threshold increased from 108 N to 168 N. The average compressive stress and compressive strain of the PBX charges were enhanced by 22.89%–108.19% and 25.75%–50.28%, respectively, with the 2.5% NC + 2.5% F 2602 composite binder delivering the optimal mechanical performance. In ignition experiments, hollow microspheres showed the highest combustion efficiency, while core-shell microspheres released energy more steadily, achieving a maximum combustion duration of 2175 ms. Theoretical calculations indicated that this composite binder system possesses a higher theoretical detonation velocity. The study confirms that adjusting the microstructure can effectively enhance the combustion and mechanical properties of composite microspheres, thereby balancing high energy with low sensitivity. The tubular continuous-flow self-assembly technology, integrated with phase separation and recrystallization principles, provides a feasible pathway for the controllable construction of composite microsphere architectures and offers a reference for the design and fabrication of other energetic composite microspheres.