Mechanochemical fabrication and properties of CL-20/RDX nano co/mixed crystals.

Xiaolan Song,Fengsheng Li,Yi Wang,Shanshan Zhao

doi:10.1039/c8ra04122a

Xiaolan Song, Fengsheng Li + Show 2 more

Open Access

https://doi.org/10.1039/c8ra04122a

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Abstract

By milling 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) together, a nano CL-20/RDX co/mixed crystal explosive with a mean particle size of 141.6 nm is prepared from the raw materials, and the co/mixed crystals are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and thermal-infrared spectrometry online (DSC-IR) technology; furthermore, the impact, friction and thermal sensitivity of the samples are tested. The results show that after milling, the morphology of the co/mixed crystal explosive is near-spherical, and the particle size reveals a normal distribution. The milled sample showed the same molecular structure and surface elements as the raw materials, but the XRD test shows that CL-20/RDX has a new crystal phase and the Raman and IR spectra gave a supplementary confirmation for the existence of a cocrystal phase in the milled sample. The activation energy of the thermal decomposition of CL-20/RDX is 206.49 kJ mol−1 higher than that of raw RDX. DSC-IR analysis showed that the thermolysis of CL-20/RDX produces a large amount of CO2 and N2O and a small amount of H2O, NO2 and NO. The mechanical sensitivity of CL-20/RDX is very low. In impact sensitivity tests with a 5 kg hammer, the special height (H50) is 51.43 cm, which is higher than the values of 36.43 cm for raw CL-20 and 9.78 cm for raw RDX. In the friction sensitivity tests, the explosion probability (P) is 56%; however, the thermal sensitivity of CL-20/RDX is higher than that of the raw materials, with its 5 s burst point being only 243.51 °C.

Highlights

IntroductionNanoexplosives show much lower sensitivities than microexplosives. cocrystallization is a good method to improve the performance of explosives
Energetic materials are usually de ned as compounds storing large amounts of energy which can burn or explode rapidly under certain external and environmental conditions.[1,2] high-energy explosives o en have problems of low safety and high cost, limiting their further development
It can be found that the O atom of N–O in CL-20 interacts with the H atom of C–H in RDX

Summary

Introduction

Nanoexplosives show much lower sensitivities than microexplosives. cocrystallization is a good method to improve the performance of explosives. The nano CL-20/HMX explosive was prepared with the spray drying method.[20] The micron-scale morphology of the cocrystal was spherical with size of 0.5–5 mm, of which the mechanical sensitivities were obviously lower than those of the raw materials. The mechanical milling method has already been used in the fabrication of drug cocrystals.[24,25] A er 34126 | RSC Adv., 2018, 8, 34126–34135. Ultra ne HMX/TATB fabricated by using this method.[26] Therein, the prepared HMX/ TATB particles were sizes of 100–300 nm, and the mechanical sensitivity of the prepared particles is lower than that of raw HMX. If the mechanical milling method was combined with nanocrystallization and cocrystallization, the sensitivity of high-energy explosives would be further reduced i.e. their safety would further be improved

Experimental

Characterization and tests

Results and discussion

Thermal analysis

Sensitivities

Conclusions