From Detonation to Afterburning: Particle Size–Driven Energy Release in CL-20-Based Thermobaric Explosives

Abstract To clarify the role of fuel and oxidizer particle size in regulating the energy output of CL-20-based thermobaric explosives, formulations with varied particle sizes were prepared and systematically investigated. Explosion calorimetry and confined explosion experiments were conducted to evaluate the effects of aluminum and potassium perchlorate (KClO 4 ) particle size on explosive energy and blast parameters. The results show that KClO 4 particle size has a negligible influence on the total explosion energy. However, reducing the particle size from 255 µm to 10 µm shortens the heat transfer distance and accelerates decomposition, thereby promoting aluminum participation in the anaerobic combustion stage. As a result, the explosion peak overpressure increases by 5.98% and 11.18%, respectively. For the 10 µm KClO 4 formulation, the elevated activation energy limits reactions, leading to a reduced quasi-static pressure. Among formulations containing single-sized aluminum powders, the Al-6 sample exhibits the highest explosion energy and pressure. This behavior is attributed to a dynamic balance between active aluminum content and reaction rate. In contrast, the graded aluminum formulation (Al-G) enables synergistic participation of different particle sizes within the reaction time window. This synergy intensifies and prolongs afterburning, resulting in the best overall explosive performance. These findings provide guidance for optimizing the energy release structure of CL-20-based thermobaric explosives.