Preparation and thermal properties study of HNIW/FOX-7 based high energy polymer bonded explosive (PBX) with low vulnerability to thermal stimulations

For modern munitions, high energy explosives are expected to reduce vulnerability and improve safety. In this study, based on the formulation of PAX-11 (94 wt% HNIW, 2.4 wt% CAB, 3.6 wt% BDNPA/F), FOX-7 is used as a portion replacement for HNIW to decrease vulnerability. To further decrease mechanical sensitivities and prevent static electricity, 0.5 wt% graphite is added to the surface of PBXs. A series of HNIW/FOX-7 based polymer bonded explosives (PBXs) with different formulations are prepared and mechanical sensitivities, thermal stabilities, detonation velocities, and slow cook-offs are studied to evaluate the energy and hazard of these PBXs. Additionally, finite element numerical simulations are utilized to study the transient temperature distributions, ignition time and ignition locations of the PBX cylinders during slow cook-off. Based on the results of this study, we obtain a high energetic low vulnerable PBX formulation (54 wt% HNIW, 40 wt% FOX-7, 2.4 wt% CAB, 3.6 wt% BDNPA/F, 0.5 wt% additional graphite) that balances energy and vulnerability. This formulation passes the slow cook-off test and detonation velocity reaches 8776 m·s⁻¹, which can be used in the warhead of the high explosive anti-tank cartridge.