Preparation And Characterization Of CL-20 Based Core-shell Structure Particle

Many high energetic explosive attract more and more attention due to its higher output energy.At the same time,there is a disadvantage that it is sensitive to the external simulation.Thus,how to reduce the sensitivity and maintain the high energy is the main focus of international researchers.The ability of explosive and the advantage of insensitive explosive with reduced sensitivity and high energy was considered in this paper.NQ was made to spherical firstly.Then CL-20/NQ composite particle was prepared by coating progress.In order to improve the defect of coated particle,CL-20/Estane/NQ composite particle was prepared.Spherical NQ,CL-20/NQ composite particle,CL-20/Estane/NQ composite particle and composite material of HMX/NQ were characterized.Spherical NQ crystal was prepared by spray crystallization method firstly 。N-methyl pyrrolidone was used as the solvent of NQ,anhydrous ethanol as nonsolvent,nickel nitrate as crystal control agent.The optimal processing conditions of preparing high bulk density spherical NQ was obtained by single factor method.The volume ratio of solvent and nonsolvent was 1:10 and the mass fraction of the crystal control agent,spray pressure,bounce frequency and stirring speed were 0.5%,0.6 MPa,40 Hz and 450 r/min,respectively.When spray was finished,ultrasonic vibration should be continued for another 20 min.The whole progress was under room temperature.The optimal spherical NQ was analyzed by standard container method,scanning electron microscopy(SEM),differential scanning calorimetry(DSC)and X-ray diffraction(XRD).The result showed that NQ obtained was spherical and the bulk density was 1.232g/cm3,which was improved by 0.943g/cm3 compared with raw material NQ;decomposition temperature determined by DSC was258.71℃,which was improved by 8.03℃ compared with that of raw material NQ.Ultrafine CL-20 was prepared by recrystallization method and the particle of drying CL-20 was dispersed into anhydrous ethanol to form the suspension secondly.The coated particle of CL-20/NQ was prepared by spray crystallization method.N-methyl pyrrolidone which consisted of NQ and nickel nitrate was sprayed into the suspension.The result indicated that CL-20/NQ coated particle had the higher activation energy and reduced thermal explosion critical temperature than the mixture of CL-20/NQ.The impact sensitivity of CL-20/NQ coated particle was improved by 10.9cm compared with the mixture of CL-20/NQ and by 32.65 cm compared with raw material of CL-20.Then,CL-20/Estane/NQ composite particle was prepared to improve the defect of CL-20/NQ.CL-20 after refining and drying was suspended in the water,and a little blinder was used to coat the particle for the first time.CL-20/Estane was obtained and CL-20/blinder composite particle was dispersed into anhydrous ethanol to form the suspension.CL-20/Estane/NQ composite particle was prepared by spraying N-methyl pyrrolidone including NQ and nickel nitrate into the suspension of CL-20/Estane.The result indicated that CL-20/Estane was coated by NQ successfully.Compared to the CL-20/NQ coated particle,the activation energy and the thermal explosion critical temperature was improved by 22.7KJ/mol,24.89℃,respectively.The impact sensitivity(H50)of CL-20/Estane was improved by 5cm compared to CL-20/NQ coated particle.Finally,HMX/NQ composite material was prepared tentatively by spray crystallization method and characterized.The results showed that HMX/NQ composite material was not the simple mixture of HMX and NQ or HMX particle coated by NQ,but the composite coating particle.The activation energy which HMX showed at the curve of DSC was improved by17.19kJ/mol compared to the raw material of HMX,but the thermal explosion critical temperature was reduced sightly.It can be concluded that the thermal stability of HMX/NQ composite material was enhanced under the origin temperature of the thermal dynamic.The impact sensitivity of HMX/NQ composite material was reduced compared to the mixture ofHMX and NQ.The H50 of HMX/NQ composite material was improved by 21.6cm compared to the mixture of HMX /NQ and by 66.9cm compared to the raw material of HMX.