Preparation And Performance Of Micron-sized Spherical RDX,CL-20 And Their Composites

Compared with ordinary explosives,spherical explosives have low mechanical sensitivity and good charging performance.In this paper,electrostatic spraying is applied to preparing spherical composite energetic material,in order to broaden its application in the field of preparation,surface modification and coating of energetic material,which is significant to develop new energetic materials.Spherical 1,3,5-trinitro-1,3,5-triazinane(RDX)and 2,4,6,8,10,12-hexanitrohexaazaisow-urtzitane(HNIW or CL-20)with the size of 1μm,were prepared by the electrostatic spray method,and the influence factors,such as voltage,receiving distance,needle size,injection rate,solution concentration and solvent composition were discussed and analyzed separately.It was found that particle size was influenced by solution composition and injection rate,while the particle morphology was affected by solution composition and receiving distance.Compared with CL-20,RDX had a smaller size.Ethanol and acetone as solvents were benefit to small size.The particle size was reduced by half when the propulsion rate was changed from 1mL·h-1 to 0.1mL·h-1.Compared with RDX,CL-20 had a better morphology.Ethyl acetate as solvent was benefit to sphere morphology.The dilute solution and the large receiving distance caused the broken particles.Composite explosives based on RDX with fluororubber(F2604),dioctyl sebacate(DOS),polyvinyl acetate(PVAc),polyvinyl butyral(PVB)and 2,4,6-Trinitromethylbenzene(TNT)were prepared by electrostatic spray method respectively.The composites had the size of 1μm-4μm.The infrared spectra and X-ray diffraction spectra of the composites were consistent with those of raw RDX,which indicated that the crystal structure of the composites did not change.In terms of the thermal properties,the thermal decomposition reaction activation energy of the composites was less than that of raw RDX.RDX/F2604 and RDX/PVAc composites,among the composites which contained 5wt%deterrent,had the largest active energy(176.348kJ·mol-1)and the highest critical temperature of the thermal explosion(219.88℃)respectively.RDX/PVAc and RDX/PVB composites had the lowest impact sensitivity(87.9cm in H50)and friction sensitivity(4%))respectively.The compatibility of the RDX/F2604,RDX/DOS and RDX/TNT composites were all in level A,which indicated good compatibility.Composite explosives based on CL-20 with F2604,DOS,PVAc,PVB and TNT were prepared by electrostatic spray method respectively.The composites had the size o 2μm-5μm.The infrared spectra and X-ray diffraction spectra of the composites were consistent with those of β-CL-20,which indicated that the crystal type of CL-20 transformed from ε to β.RDX/F2604 composites,among the composites which contained 5wt%deterrent,had the largest thermal decomposition reaction active energy(325.771kJ·mol-1),the highest critical temperature of the thermal explosion(231.67℃),the lowest impact sensitivity(42.8cm in H50)and the lowest friction sensitivity(64%).The compatibility of the composites was in level C or D,which indicated poor compatibility.Composite explosives based on CL-20with RDX,1,3,5,7-Tetranitro-1,3,5,7-tetrazocane(HMX)and 3-Nitroso-1,2,4-triazol-one(NTO)were prepared by electrostatic spray method.The composites had the size of 1μm-2μm.The composites had different structures with different molar ratios.CL-20/HMX composites,among the composites with the 1:1 molar ratio,had the largest thermal decomposition reaction active energy(404.860kJ·molol-1),the highest critical temperature of the thermal explosion(225.49℃)and the largest deflagration pressure(922kPa).Composite explosives based on ammonium perchlorate(AP)and RDX,CL-20,NTO and TNT were prepared by electrostatic spray method.The AP/explosive composites were 5μm irregular particles.There was interaction between AP/CL-20,AP/NTO and AP/RDX composites.AP/CL-20 composites had the largest active energy(432.692kJ·mol-1)and the largest deflagration pressure(1226kPa),AP/TNT composites had the highest critical temperature of the thermal explosion(281.97℃).The binding energy of the RDX/DOS system and the CL-20/DOS system calculated by molecular dynamics simulation under COMPASS force field was 150.6kcal·mol-1 and 128.2kcal-mol-1 respectively.Under ReaxFF force field,the initial thermal decomposition mechanism of CL-20/RDX system was analyzed,and the main initial thermal decomposition products of the system were NO2,HONO and CHN2O2.Spherical RDX and CL-20,insensitive agent composite explosives,CL-20/explosive composites and AP/explosive composites could be prepared by the electrostatic spray method,which realized the explosive partciles’ surface modification and coating,the assembly and mixing of multi-component explosive in micro-nanometer scale,and improved the performance of the explosives effectively.