Aluminum hydride is a promising candidate for application in energetic materials and hydrogen storages. E.g. an AP/HTPB rocket propellant filled with alane was calculated for a 100 N s kg À1 higher specific impulse compared to the same concentration of aluminum. Different investigations on a-AlH 3 polyhedra using thermoanalytical methods and X-ray diffraction were performed to receive a better understanding of dehydration at about 450 K, passivation of the remaining porous aluminum particles and further oxidation. A modeling approach to describe these conversions including diffusion processes, Avrami-Erofeev mechanism and Arrhenius type reaction steps of n-th order were introduced. Results were discussed in comparison to experimental investigations under pressure with model propellants on the base of gelled pure nitromethane and also filled with alane or pure aluminum in concentrations of 5%, 10% and 15%. Both alane and aluminum increase the burning rate on a factor of two correlated with a temperature increase up to 500 K and more. A mesa burning effect at 6 to 10 MPa was indicated by the mixtures with alane.
Ytterbium metal powder burns with a luminous vapor phase diffusion flame in oxygen. Consolidated stoichiometric mixtures with both polytetrafluoroethylene and hexachloroethane upon ignition yield intense luminous flames. With UV/Vis spectroscopy of the combustion flames Yb, YbO, YbCl, and YbF species have been identified contributing to the selective emission in the green spectral range. The flame temperatures of ytterbium combustion in oxygen and with halocarbon based oxidizers are in the same range as for comparable magnesium based systems.
Deceiving with TNT: Melt‐cast pyrotechnic mixtures based on 2,4,6‐trinitrotoluene (TNT)/KClO4 (see picture for flame) spectrally matched infrared decoy flares and show superior performance and greatly reduced sensitivity in comparison to common pyrotechnic or double‐base material currently in use for IR countermeasure flares.
In the presented work two experimental pyrolants for use in blackbody infrared decoy flares showing higher performance than baseline magnesium/polytetrafluoroethylene/Viton® (MTV) were investigated. These pyrolants are based on fuels hitherto unknown to pyrotechnics: magnesium diboride, MgB2, and dimagnesium silicide, Mg2Si. Both fuels were formulated with polytetrafluoroethylene, PTFE and a fluorocarbon binder Viton® (designated MbTV and MsTV). MsTV yields higher radiance, Lλ (W cm−2 sr−1) in the mid infrared range (2–5 μm) than MTV at same stoichiometry. The volumetric spectral efficiency Eλ (J cm−3 sr−1) of MbTV is also superior to MTV. MbTV thus allows for size reduction of black body countermeasure flares and thereby has potential to enhance the survivability of aircraft in hostile environments. Due to its very high burning rate MsTV qualifies for first fire and igniter applications.
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