Abstract
In order to improve the safety of hexanitrohexaazaisowurtzitane (CL-20), submicron CL-20 particles were prepared by a siphon ultrasonic-assisted spray refining experimental device. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), and the impact sensitivity of the samples was tested. The results show that the particle size of siphon-refined CL-20 is about 800 nm~1 μm, which is more smooth, mellow, and dense than that of CL-20 prepared by a traditional pressure-refined method. The peak diffraction angle of pressure- and siphon-refined CL-20 is basically the same as that of raw CL-20, and their crystal forms are ε type. The peak strength of pressure- and siphon-refined CL-20 decreased obviously. The apparent activation energy of pressure-refined CL-20 and siphon-refined CL-20 is 13.3 kJ/mol and 11.95 kJ/mol higher than that of raw CL-20, respectively. The thermal stability of CL-20 is improved. The activation enthalpy (ΔH#) is significantly higher than that of raw CL-20, and the characteristic drop is 70.4% and 82.7% higher than that of raw CL-20. The impact sensitivity of siphon-refined CL-20 is lower than that of pressure-refined CL-20, so the safety performance of an explosive is improved obviously.
Highlights
With the increasing military demand, high-energy explosives have developed rapidly
Due to its high mechanical sensitivity and multifaceted crystal, it cannot meet the needs of explosive safety performance in the battlefield environment, so it needs to be refined to obtain highquality crystal to meet the requirements of explosive safety performance
The results show that CL-20 nanoparticles are spherical or ellipsoidal with an average particle size of 95 nm
Summary
With the increasing military demand, high-energy explosives have developed rapidly. Nanoparticles of CL-20 are spherical with an average diameter of 25 nm Another method is to spray CL-20 solution into nonsolvent (isooctane) with ethyl acetate as solvent and prepare nano-CL-20 by precipitation crystallization. Results show that the superfine CL-20 particles obtained with low-density grinding balls are spherical, its mechanical sensitivity is significantly reduced, its thermal stability is better than raw CL-20, and the polymorph remains ε type. Pang et al [18] prepared ultrafine spherical CL-20 particles by means of a compressed air spray device. The principle of siphon air atomization was compared with the traditional atomization method to prepare fine CL-20 particles.
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