Abstract
Over the past century, the search for advanced melt-cast explosives with high energy and good safety has been a highly challenging task in the field of high explosives. Here, the casting carrier 3,5-difluoro-2,4,6-trinitroanisole (DFTNAN) and the high-energy component 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) were taken as examples to design a new melt-cast explosive with the dual advantages of high energy and low sensitivity. At the micro level, molecular dynamics method was used to theoretically study the binding energy, cohesive energy density, radial distribution function, and mechanical properties of DFTNAN/CL-20 systems with different mass ratios. The results showed that under the set research conditions, the system with mass ratio of 40:60 had the highest binding energy and cohesive energy density, and the intermolecular interaction (e.g., hydrogen bond) between DFTNAN and CL-20 was the strongest, indicating that the system had the best stability. Furtherly, the calculation on mechanical properties showed that compared with CL-20, the K/G and Cauchy pressure values of DFTNAN/CL-20 system with the mass ratio of 40:60 increase, while its K, E, and G values decrease, demonstrating that the system has changed from rigid to flexible, and the safety has been improved. On this basis, the optimized mass ratio of DFTNAN/CL-20 system was determined as 40:60. At the macro level, the safety performance of the optimized DFTNAN/CL-20 system (40DFTNAN/60CL-20) including mechanical sensitivity and thermal sensitivity was tested experimentally. The results confirm that compared with CL-20, the safety of 40DFTNAN/60 CL-20 was improved on the friction sensitivity decreases by 60%, the impact sensitivity decreases by 8%, and the thermal sensitivity increases from 228.81 to 248.96 degrees C. In addition, the energy level assessment showed that the measured detonation velocity is 8260 m.s(-1), which is 6.7% higher than that of traditional B explosive (40TNT/60RDX), demonstrating that 40DFTNAN/60CL-20 is a low-sensitive high-energy explosive.