Study On Desensitization Technology Of HMX And CL-20 Explosives By Crystallization Method

As nitroamine explosives with excellent comprehensive performance,HMX and CL-20 have been widely used in weapon charge and solid propellant.In order to meet the development of high energy blunt effect of ammunition,scholars of various countries have developed different formulas of composite explosives,in order to improve the comprehensive performance of HMX and CL-20.This paper explored the sensitivity reduction technology of HMX and CL-20 by means of coating and eutectic respectively,in order to further optimize the sensitivity reduction technology of nitroamine explosives and promote the technological production and application.In order to decrease the susceptibility of HMX,the insensitive explosive 1,1-diamino-2,2-dinitroethylene(FOX-7)was used to decrease the susceptibility of HMX.FOX-7/HMX composite explosive was prepared by cooling crystallization,spray crystallization and low-temperature vacuum drying,focus on the selection of preparation conditions and process optimization,and explore the feasibility of process scaling.The particle size of raw materials,feeding ratio,solvent type,solvent/water ratio,solution saturation and other factors were screened through experiments.Through experiments,the experimental conditions conducive to the formation of coating under different processes were explored to improve the compactness of coating and the properties of the product,and the composite explosive with reduced sensitivity was obtained.The morphology,structure,thermal decomposition performance and impact sensitivity of the composite explosive were compared and analyzed,and the influence of different processing methods on the comprehensive performance of the composite explosive was investigated,providing a reliable basis for the HMX coating sensitivity reduction process.In order to explore the applicability of the process,the spray crystallization process was applied to the susceptibility reduction study of 3-nitro-1,2,4-triazole-5-ketone(NTO)coated HMX,and a better composite product was obtained.Experimental results show that the product obtained by the coating process is a composite of FOX-7 coated on the surface of HMX.When FOX-7 and HMX feeding ratio is 1:1 and solvent is DMF,the coating effect of low temperature vacuum drying coating process is the best.The initial decomposition temperature of FOX-7/HMX composite explosive is 21.8 ℃ higher than that of the components,showing good thermal stability,and the impact sensitivity is significantly lower than that of HMX.The eutectic technology was used to study the sensitivity reduction of CL-20,and three eutectic preparation methods including hydrothermal method,vacuum drying method and solvent volatilization method were used to explore the eutectic experiment of CL-20/FOX-7and CL-20/TNT systems.In the preparation of CL-20/TNT eutectic by solvent evaporation method,ethyl acetate and methanol with volume ratio of 1:1 were selected as the mixed solvent.A new peak appeared and CL-20 did not transform,so it could be judged that a new crystal was obtained,but no single crystal was cultivated.In order to expand the preparation method of eutectic single crystal,hydrothermal method and vacuum drying method were applied to the preparation of eutectic single crystal.In the experiment of eutectic preparation by hydrothermal method,the influences of pre-grinding time,hydrothermal time and pressure on crystal growth were investigated.The effects of solvent,drying time and solution saturation on the eutectic formation of CL-20/FOX-7 by vacuum drying were investigated.After a large number of screening experiments,the experimental results were characterized and analyzed,and the experimental conditions affecting eutectic formation were obtained based on hydrothermal method and vacuum freeze drying.