Shock-induced chemical decomposition and detonation in HE single crystals: Comparing an insensitive HE (FOX-7) and a conventional HE (RDX)

Understanding the differences in the shock and detonation response of insensitive high explosives (IHEs) and conventional HEs (CHEs) is a long-standing need in HE science and technology. To address this need, a comprehensive effort was undertaken to examine the response of FOX-7 (IHE) and RDX (CHE) single crystals subjected to well-defined shock compression to ~63 GPa. Wave profiles in RDX single crystals shocked along the [100] and [111] orientations showed decomposition onset at 15 GPa – less than half the onset stress observed for FOX-7 (~32 GPa) – demonstrating the strong shock insensitivity of FOX-7. The classic Chapman–Jouget (C–J) detonation response was observed at a higher stress (51 GPa) for RDX than for FOX-7 (44 GPa), despite the lower decomposition onset for RDX. Although the measured C–J pressures (35 GPa) are comparable for RDX single crystals and FOX-7 single crystals, the Hugoniot states for the FOX-7 detonation products lie above those for RDX in the P–V plane, suggesting higher performance for FOX-7 at overdriven detonation conditions. The present findings provide the first experimental comparison of the shock compression and detonation response of conventional and insensitive HE single crystals at pressures below and above the C–J pressure.