Formulation Design, Direct-writing Regulation And Explosion Propagation Performance Of Energetic Nano CL-20 Ink

In order to find a appropriate method to make the booster explosives exist in explosive train of MEMS initiating explosive devices charged in microscale, based on direct writing technology, experiments were carried out by combining MicroPen deposition direct writing technology, which was applied in nano-CL-20 energetic ink, with traditional initiating explosive devices technology. The main contents and conclusions are shown as follows:(1) The stability of the ink formulation was studied, which was influenced by three kinds of binders and the content of CL-20. The results indicate that by using fluorine rubber as a binder, only the sol state CL-20 ink shows better stability. Meanwhile, by Using nitrocellulose as the binder, both the sol state CL-20 and the suspended state CL-20 show better stability.(2) The rules that direct writing linewidth of energetic ink influenced by direct writing pressure, MicroPen nozzle diameter and ink viscosity was researched. The results indicate that as the ink viscosity decreasing, ink direct writing pressure, MicroPen tip diameter increase and write-width all increases. However, the growing rate of pressure was in a linear relationship with that of the linewidth increasing. When the ink viscosity decreases, the growing rate of linewidth decreases too. With the increasing of MicroPen inner diameter, the growing rate of width increases significantly. In the meantime, during the experiment of direct write-charge, write-linewidth should be controlled so as to prevent air being mixed in the ink.(3) Based on FLUENT6.3, we established a flow model for energetic ink flew in MicroPen. The simulation results show that direct write micro ink water flow is laminar flow rate, which rises linearly with the growing of pressure.As the viscosity increases, the velocity of ink decreases and the decreasing speed reduces accordingly. Flow velocity and the speed is increasing with micropen diameter increasing.(4) Respectively using fluorine rubber and nitrocotton as binders, three groups of energetic ink were produced. Charged by MicroPen direct writing deposition technique, booster performance of three groups ink were tested. The results show that when the mass fraction of ink component CL-20, nitrocotton, butyl acetate and UV curing agent were 41.5%, 2.1%,53.9% and 2.5%, respectively, the direct writing ink solvent evaporated after the charge. Then, the content of CL-20 would reach the level of 90%, whose detonation velocity is greater than 7000 m/s and booster critical diameter is about 0.28mm.(5) LS-D YNA software was used to simulate the booster pressure and the booster limit thickness of energetic nano-CL-20 ink charged in microsize. The results indicate that the peak pressure of CL-20 explosive stable detonation is about 15GPa. At the same time, the critical size for steady spread of CL-20 explosive detonation is about 0.31mm, which is similar with the experimental value 0.28mm. The result mean that the simulation results are reliable.(6) The feasibility of propagation of explosion in microscale Charge was study for improving applications of CL-20 ink direct write technology in microscale charge. Testing results show that nano CL-20 ink is able to generate stable detonation in the mold with size of 500μm × 500μm × 60mm through MicroPen direct write deposition charge technology. It prove that suspended CL-20 ink formulation fullfills a preliminary requirment of engineering application.