Preparation And Properties Of Low Sensitivity CL-20 Matrix Composite Particles

With the continuous progress of science and technology,a wide variety of high-energy materials are emerging.However,the structure of energetic materials contains explosive groups,so it is easy to accidentally explode in the process of storage and use.How to improve its safety has become a big problem.CL-20 is one of the single explosives with the highest density and energy in the world and has a wide application prospect in mixed explosives and propellants.However,the inherent contradiction between energy and safety has made CL-20 sensing reduction a research priority at home and abroad.In order to meet the application requirements of CL-20,aqueous suspension method was adopted in this dissertation,with CL-20 as the main explosive and FOX-7 and WAX as the dull sensitizer.After screening the technological parameters,CL-20/FOX-7/WAX explosive particles were successfully prepared,and their properties were studied.The main research results are as follows.First of all,the optimum process conditions for the recrystallization of FOX-7were determined.The optimum process conditions were determined by using the single factor method,selecting solvent type,solution concentration,solvent/non-solvent volume ratio,stirring speed and drop acceleration rate as the influencing factors,and using particle morphology and friction sensitivity results as the evaluation criteria,NMP is solvent,water is non-solvent,solution concentration is0.12 g/mL,solvent non-solvent ratio of 1 to 12,rotation speed is 300 r/min,droplet acceleration is 7μL/s.The FOX-7 crystals obtained by this process were spherical in shape,with an average particle size of 5.93μm and an increased critical load of 132 N on the frictional susceptibility.Secondly,CL-20/FOX-7 explosive pellets were prepared by the aqueous suspension method according to the optimum process conditions,and the performance was compared with that of the mechanically mixed sample.The results show that the aqueous suspension method can effectively improve the coating rate;the apparent activation energy of the mechanically mixed sample and the aqueous suspension sample increased by 18.39 kJ/mol and 177.53 kJ/mol respectively compared with the raw material;the critical load of frictional susceptibility of the two samples increased by 52 N and 108 N respectively,and the degree of percussion sensitivity H₅₀increased by 10 mm and 17 mm respectively.The performance of aqueous suspension method is better.However,scanning electron microscope results showed that some crystal planes of CL-20 were not coated by FOX-7,and the ideal effect could not be achieved only by FOX-7 coating.Based on this,CL-20/FOX-7/WAX composite particles were prepared by introducing a wax passivant to improve the coating effect.The effects of passivate type,coating sequence and passivate ratio on the coating effect and performance of the composite particles were investigated.By comparing the morphology,coating rate,thermal stability and friction sensitivity of each sample,the coating rate of 5%microcrystalline wax is 81.11%,the critical load of friction sensitivity is 360 N,and the reduction of friction sensitivity is the best.Finally,the performance of CL-20/FOX-7/WAX composite pellets and CL-20/FOX-7 explosive pellets were compared.The results show that the composite cladding increased the cladding rate by 14.89%,the peak thermal decomposition temperature by 2.62°C,the critical load for frictional susceptibility by 192 N and the degree of percussion sensitivity H₅₀increased by 21 mm.All these results indicate that the composite cladding can significantly improve the application performance of the explosive pellets compared to the single cladding.