Coating of High Melting Explosive Particles by Nitrotriazolone to Formulate Composite Nanoparticles by Spray Flash Evaporation

ABSTRACT The balance between performance and safety of high explosives is at the heart of the current studies, and new ways of combining safety and performance have hence been elaborated. This study focuses on a mixture of 3‐nitro‐1,2,4‐triazol‐5‐one (NTO) and octogen (high melting explosive [HMX]). On the one hand, NTO is a well‐known explosive with low sensitivity. Its impact sensitivity threshold of 9 J makes it one of the safest explosives. On the other hand, with a detonation velocity of 9.1 km/s ( ρ = 1.91 g/cm 3 ), HMX is one of the most powerful high explosives in use. In this study, different HMX@NTO nanoparticles have been produced with the use of the spray flash evaporation process, developed and patented in the NS3E laboratory. The obtained structures have been characterized by Raman spectroscopy, confirming that HMX was indeed coated by NTO in a core‐shell structure. Scanning electron microscopy pictures proved that the particle sizes were submicrometric. Powder X‐ray diffraction analysis revealed that the HMX shifted to its δ‐phase during the process. Differential scanning calorimetry analyses showed that the samples decomposed in a one‐step, HMX‐driven process, thus confirming the homogeneity of the mixture, but showing a thermal sensitization. Sensitivity measurements showed that the samples tested had an impact initiation threshold two times higher than pure HMX, while detonation velocity measurements resulted in values higher than NTO's, and in agreement with calculated data. Furthermore, those detonations occurred in small‐diameter tubes (3 mm), which proves that our compositions have small critical diameters.