Explosives are compounds or mixtures which produce hot compressed gas reacted by impact or electrical shock. To reduce sensitivity of explosive materials, we focused on reducing internal defects in explosives. Research Department eXplosive(RDX) is high energetic material which is more powerful than TNT, most general explosive. To decrease sensitivity of RDX, we micronized the RDX particle by a precipitation process. When RDX particle gets smaller, sensitivity also gets lower, because small particle can decrease the size and number of hotspots. We used Rapid Expansion of Supercritical Solvent process called RESS. We analyzed the sample with elemental analysis, FE-SEM, XRD, FT-IR.
In this study, 6 kinds of screw arrangements are assumed and simulated dynamically by Computational Fluid Dynamics(CFD) for calculating mixing efficiency of particles and physical characteristic of each kneading block. Mixing efficiency is analysed in terms of distributive mixing and dispersive mixing. For dispersive mixing, Manas-Zloczower mixing index was introduced and for distributive mixing, particles motion which injected to opposite side and colored differently was observed. As a result, 515N block shows the maximum efficiency for both mixing schemes and 515L block shows better mixing effect than 515R block in terms of distributive mixing but shows worse mixing effect in terms of dispersive mixing.
An improvement of a performance and an insensitivity of high energetic materials(HEMs) is very important evaluation index in a research of HEMs. Studies on the improvement of the insensitivity against a external unintended stimuli rather than the performance owing to stability have been done for decades. Current researches focus on to control of a size of crystal for reducing the number and the size of the internal defects because the internal defects are worked as the trigger of explosion by the external stimuli. In this work, nano-sized HEMs were producted by drowing-out or milling/crystallization and the improvement of insensitivity of them was confirmed. The effect of a spraying distance, a concentration of solution, a temperature of solution/antisolvent on the size of crystals were investigated.
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