Study On The Reaction Properties Of Al/Fe₂O₃-RDX Nanocomposites

In the paper, a type of novel, potentially green primary explosive: Al/Fe2O3-RDX nanocomposites, were designed and successfully prepared. Based on the research of the properties of their basic constituents(nano-Fe2O3 and Al/Fe2O3 nanothermites) which possess great effect on their reaction properties, their reaction properties in the primary explosive field were studied in detail. And the application performances in the bridgewire detonators were evaluated. The main contents of the paper are as follows:(1) Based on the sol-gel reaction theory, nano-Fe2O3 was prepared by the sol-gel method connecting supercritical fluid technology. The effects of the sol-gel process conditions and the supercritical process parameters on the properties of the Fe2O3 xerogel were fully studied, and the sol-gel reaction mechanism was analyzed. The crystal phase,morphology and pore structure of the nano-Fe2O3 prepared at different calcining temperatures were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscope(TEM) and specific surface area and pore analysis. Nano-Fe2O3 with different specific surface area and pore structures could be obtained through adjusting the heat treatment temperature of xerogel.(2) The Al/Fe2O3 nanothermites and Al/Fe2O3-RDX nanocomposites with different ingredient proportions were prepared through the ultrasonic mixing method and adjusting the stoichiometric ratio of nano-Al, nano-Fe2O3 and RDX. The combustion properties of Al/Fe2O3 nanothermites in the glass tube were tested in weak constrained conditions through the high speed video, and the effects of the glass tube diameter, the loading density,the equivalence ratio of Al and Fe2O3 in the Al/Fe2O3 nanothermite, the specific surface area of Fe2O3 on the combustion wave speeds were discussed in detail. Based on these results, the combustion mechanism of Al/Fe2O3 nanothermite in weak constrained conditions was fully analyzed. And Al/Fe2O3 nanothermite with high combustion rate was obtained.(3) Based on the thermal reaction kinetics, the thermal properties of Al/Fe2O3 nanothermite and Al/Fe2O3-RDX nanocomposite were studied through the differential scanning calorimetric(DSC)method at different heating rates, and the Kissinger equation of the thermal reaction kinetics of the nanocomposite was achieved. Based on these results,the catalytic decomposition mechanism of nanocomposite was suggested. These lay atheoretical foundation for the fast deflagration to detonation transition(DDT) of Al/Fe2O3-RDX nanocomposite.(4) Based on the DDT theory of the high explosives, the combustion wave speeds and DDT process of Al/Fe2O3-RDX nanocomposites in the quartz glass tube(or the organic glass tube) were recorded through the high speed video and the effects of the glass tube material, the glass tube diameter and the ingredient proportions on the firing conditions,combustion, DDT process and DDT mechanism of Al/Fe2O3-RDX nanocomposites were discussed in detail. Based on these results, the physical model of the DDT process of nanocomposites was suggested and the DDT mechanism was gained. Finally, the Al/Fe2O3-RDX nanocomposites with fast DDT were obtained.(5) The thermal stability of Al/Fe2O3-RDX nanocomposite was investigated by the DSC method, and the mechanical sensitivities, the static discharge sensitivities, the flame sensitivities and the hot bridge wire sensitivities were measured as a function of the particle sizes and amount of the constituents of nanocomposites. The Al/Fe2O3-RDX nanocomposites with different sensitivities and detonation power were obtained and their sensitivities in the field of primary explosives were achieved.(6) Al/Fe2O3-RDX nanocomposites were loaded in the electric detonators, and their ignition properties and the damage effects on the electric detonators were investigated.Their ignition delay time, front time and peak pressure in the constant volume combustion were measured through the closed bomb test, and the effects of the ingredient proportions,the mixing solvents, the specific surface area of Fe2O3, the loading pressures on the constant volume combustion properties were discussed in detail. The functional relationship between the peak combustion pressure and the RDX contents was suggested, and some relevant factors were analyzed. The application performances of Al/Fe2O3-RDX nanocomposites in the bridgewire detonators were obtained.