Abstract:To improve the storage stability of potassium borohydride(KBH₄), sodium borohydride(NaBH₄) and lithium aluminum hydride(LiAlH₄), KBH₄ and NaBH₄ were coated by paraffin via solvent-nonsolvent method and LiAlH₄ was coated by naphthalene via recrystallization. The surface coating stafas of the samples was studied by SEM, FTIR and XRD and the combustion properties of the propellants added into coated sample were tested by an Infrared Thermometer. Results show that KBH₄, NaBH₄ and LiAlH₄ are completely coated and the coating stafas of NaBH₄ is the best. The combustion properties of propellant added with coating-NaBH₄ sample are significantly improved and the burning rate is increased by more than 5%.

Abstract:The Al-Ni-Ti-Zr non-equilibrium alloy powder was prepared by mechanical alloying method. The Al-Ni-Ti-Zr non-equilibrium alloy powder/polytetrafluoroethylene(PTFE) reactive materials were prepared via mixing/pressing using Al-based non-equilibrium alloy powders and PTFE micro powders. The phase composition and morphology characteristics of the powders during ball milling were characterized by X ray diffraction(XRD) and scanning electron microscopy(SEM). The phase structure of the milled alloy powders was analyzed by high resolution transmission electron microscopy(HRTEM) and selected area electron diffraction(SAED). The thermal behaviors of non-equilibrium Al/PTFE reactive materials were examined by differential scanning calorimetry(DSC). The results show that the Al-based non-equilibrium alloy powders can be prepared by mechanical alloying method. There is a nano scale micro-crystalline island area dispersed in amorphous phase matrix. The peak temperature and exothermic peak area of non-equilibrium Al/PTFE reactive materials at a heating rate of 10 K·min^-1 in air are 495 ℃ and 1775 J·g^-1, respectively. Under the continuous heating condition, the exothermic reaction of the non-equilibrium Al/PTFE reactive materials has the typical kinetic characteristics, and the activation energy E_c of the reaction is calculated as 309.1 kJ·mol^-1 by Kissinger method.

Abstract:To study the effect rule of the type and size for polysilicon bridge on the ignition performance of Al/CuO energetic igniter, six kinds of energetic igniters with different shapes and sizes were prepared by integrating polysilicon with Al/CuO multilayer films and the firing sensitivities of four sizes and two bridges-a total of six kinds of igniters(S, M, Lr, Lv, Hr, Hv)were tested by employing the Neyer D-optimal sensitivity method. The critical electro-exploding voltages of the igniters were explored. The change rule in firing time with the excitation voltage was obtained. The ignition performances of polysilicon igniter and energetic igniter were comparatively studied by sensitivity test and ignition test. Results show that the sensitivity and firing time decrease with increasing the bridge film volume, and the V-type-angle bridge film helps to decrease the action time and energy needed for the action. The 50%-firing voltage of 8.70 V and standard deviation of 0.53 of the polysilicon igniters are higher than those of the energetic igniters (8.19 V, 0.14). Due to the energy release during chemical reaction of Al/CuO multilayer films, average firing time of 52.85 μs of the energetic igniters at 14 V is much lower than that of 109.12 μs of the polysilicon igniter at 14 V and this difference decreases with the increase of excitation energy.

Abstract:To study the effects of ingredients in formulation on the performance of deflagration to detonation transition(DDT) for dinitrofurazanfuroxan(DNTF) based explosives, three kinds of formulations that the molar ratio of AP and Al powders is 0.306, 0.414 and 0.574, were designed. The performance test of DDT for three kinds of DNTF-based composite explosive formulations was carried out by the coaxial ionization probe test technology. The influence of molar ratio of AP and Al powders on the deflagration to detonation transition of explosive was analyzed by change of wave front velocity and inducement detonation distance. Results show that with increasing the molar ratio of AP and Al from 0.306 to 0.574, the initial burn duration time increases from 1065 μs to 1395 μs, and the burning rate decreases from 141 m·s^-1 to 108 m·s^-1, but the duration time of convection combustion section and deflagration section decreases rapidly, and the convection burning rate increases from 500 m·s^-1 to 1668 m·s^-1, and deflagration velocity increases from 3000 m·s^-1 to 4800 m·s^-1, the inducing detonation distance occurring DDT decreases from about 675 mm to 425 mm.

Abstract:The reactive Al/Fe₂O₃/PTFE material was prepared by molding and sintering method. The quasi-static compression feature and impact sensitivity of Al/Fe₂O₃/PTFE material molded in different proportioning and at different sintering temperature were comparatively tested by universal testing machine, drop hammer machine and high-speed photography instrument. Its ignition performance was analyzed. Results show that: specimens with 60% and 70% polytetrafluoroethylene(refer to as PTFE) sintering at 330 ℃ have the highest strength and the maximum real stress is 46 MPa. Specimens with 40% PTFE sintering at 350 ℃ have the highest impact sensitivity, and its characteristic drop height H₅₀ is 95 cm. The Al/Fe₂O₃/PTFE material under the impact ignition conditions will appear the high temperature metal slag jet phenomenon. The research results have raised the understanding of the deformation behavior and impact reaction of Al/Fe₂O₃/PTFE material, which has laid a good foundation for the following research.

Abstract:Ternary Al-Mg-Zr alloy fuels with Mg content ranging from 5% to 30% were prepared by a close-coupled gas atomization. The phase composition, morphology and exothermic oxidation behavior of the alloy powders were characterized by X-ray diffraction, scanning electron microscope(SEM)/ energy dispersive spectrometer (EDS) and thermogravimetry-differential thermal analysis (TG-DTA) respectively and an oxidation reaction mechanism model was proposed to explain the intensive oxidation exothermic phenomenon. Results show that the alloy powders consist of Al, Al₃Mg₂, Al₃Zr and Al₁₂Mg₁₇ mainly, and the powder has good sphericity. With the increasing of Mg content, the oxidation reaction temperature of Al-Mg-Zr alloys decreases, the multi-step oxidation process gradually transforms into single step oxidation process and the energy releasing amount increases first and then decreases. The intensive exothermic oxidations of Al₇₈Mg₂₀Zr₂ and Al₇₃Mg₂₅Zr₂ powders occur at 945 ℃ and 938 ℃, respectively. The intensive oxidation reaction of Al₇₈Mg₂₀Zr₂ powder is relatively complete and the highest exothermic enthalpy of oxidation of the powder is 9798.8 μV·s·mg^-1.

Abstract:To improve the explosion energy of nitric ester explosive, boron-containing hydrogen-storage-alloy (Mg(BH_x)_y) was added into nitric ester explosive. The explosion energy and after burning effects of nitric ester explosive with Mg(BH_x)_y were studied by underwater explosion test and explosion test in air. Results show that Mg(BH_x)_y can significantly improve the explosion energy of nitric ester explosive. In explosion test in air, Mg(BH_x)_y is decomposed, and the decomposition products are involved in the detonation reaction. In underwater explosion test, after adding Mg(BH_x)_y, the explosion energy of the nitric ester explosive is increased by 17.56%, and the nitric ester explosive with Mg(BHx)y has an obvious after burning effect.

Abstract:The boron-based propellant samples were prepared through coating boron particles with a recrystallization method selecting ammonium perchlorate(AP), ammonium nitrate(AN), nitroguanidine(NQ) and octogen(HMX) as four kinds of oxidants. The effect of different oxidant coating on the ignition and combustion characteristics of boron-based propellant was studied by using TG-DSC and laser ignition test system. The mechanical mixing sample was set as control group. Results show that AP coating can induce low-temperature deflagration of the sample, so as to promote the low-temperature oxidation of boron particles. It helps to effectively shorten the ignition delay time of the sample to 330 ms. By comparing with the mechanical mixing sample, the recrystallization method was found to be the main cause of low-temperature deflagration of the sample. The sample coated by AN has a lower initial reaction temperature of 327.6 ℃. However, its whole exothermic properties are poor, the average combustion temperature is only 642.8 ℃. The coating of NQ and HMX can effectively improve the combustion strength of B-based propellants, shorten the combustion time. Among them, NQ can help to improve the maximum combustion intensity. HMX is more conducive to the upgrade of the whole combustion intensity. The coating of HMX makes the combustion time of B-based propellant shorten to 2750 ms, the average combustion temperature reaches 845.5 ℃ and the heat release is raised to 9968 J·g^-1.