Applied Research Of Nanometer RDX/HMX Based TNT-Melt-cast Explosive

As the second-generation high-energy materials, RDX and HMX, are widely used as the main explosive in a variety of weapon charges, owing to their special detonation performances. However, the industrial micron-sized RDX and HMX are highly sensitive and as-prepared melt-cast explosives have high sensibilities when they are applied into TNT-RDX or TNT-HMX melt-cast explosives with the presence of voids, cracks, bubbles and other internal defects, causing many safety problems. Recent studies show that the sensitivity of RDX and HMX was significantly reduced by use of nanotechnology. In this paper, nano-RDX and nano-HMX were applied into TNT-based melt-cast explosive and their effects on the sensitivities, thermal decomposition characteristics and mechanical properties of as-prepared melt-cast explosives were also studied. Specific research contents are as follows:Firstly, the viscosity and effective solid content of RDX-TNT-based melt-cast explosive were researched and the results indicated that the effective solid content decreased with the reduction of the average particle size of RDX when RDX with single particle size was used in TNT-based melt-cast explosive. At the same time, the effective solid content significantly increased from 66.7% to 71% with the addition of ultrafine RDX, especially nano-RDX when using RDX with different particle sizes. By analyzing the SEM images Of the cross section of the melt-cast explosive,the defects of the melt-cast explosive containing nano-RDX were fewer when the holding temperature was 50℃ and the holding time was 12h.Then, the thermal decomposition characteristics, sensitivities, mechanical properties and detonation performance of TNT-based melt-cast explosive containing nano-RDX were researched. The results exhibited that comparing to TNT-based melt-cast explosive containing industrial micron-sized RDX, with the addition of nano-RDX, the thermal decomposition peak temperatures increased gradually, while the termination decomposition temperatures lagged behind with the apparent activation energy decreasing. Besides, when adding 20% of nano-RDX, the impact sensitivity of TNT-based melt-cast explosive containing nano-RDX decreased by 10.25% with the friction sensitivity decreasing by 25%, while the compressive strength, shear strength, tensile strength improved by 9%,107.01% and 50%, respectively, with the comparative detonation velocity.Thirdly, the study on the viscosity and effective solid content of HMX-TNT-based melt-cast explosive was conducted. And the results revealed that with the decrease in the average particle size, the effective solid content decreased a little when adopting HMX with single particle size in TNT-based melt-cast explosive. Meanwhile, the effective solid content remarkably increased with the addition of ultrafine HMX, especially nano-HMX when HMX with different particle sizes was used. On the basis of the SEM images, the defects of the melt-cast explosive containing nano-HMX were found to be fewer when the holding temperature was set at 50℃ and the holding time was kept up to 12h.Lastly, the thermal decomposition characteristics, sensitivities, mechanical properties and detonation performance of TNT-based melt-cast explosive containing nano-HMX were researched. The results showed that comparing to TNT-based melt-cast explosive containing industrial micron-sized HMX, with the addition of nano-HMX, the thermal decomposition peak temperatures increased gradually, while the termination decomposition temperatures lagged behind with the apparent activation energy decreasing. Besides, when adding about 7.5% of nano-HMX, the impact sensitivity of TNT-based melt-cast explosive containing nano-HMX decreased by 15.7% with the friction sensitivity decreasing by 21.4%, while the compressive strength, shear strength, tensile strength improved by 35.18%,35.29% and 56.49%, respectively, with the comparative detonation velocity.