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2009 | Vol. 6, nr 3-4 | 277-289
Tytuł artykułu

Mechanical Activation of Al/MoO3 Thermite as a Component of Energetic Condensed Systems to Increase Its Effciency

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In the present work a stoichiometric energetic compositions Al+MoO3 prepared by dry mixing and by reactive milling of micro-scale particles were investigated. Morphology, particle size and surface structure of produced powders were examined using scanning electron microscopy, atomic-force microscopy, laser diffractometry and BET analysis. DSC/TG data were processed to obtain kinetic mechanism of the reaction between Al and MoO3. The combustion rate of Al+MoO3 thermite mixture increases with pressure, reaching a maximum at ~10 atm, and then decreases with further pressure increase. The rise of combustion rate at the low range of pressure is associated with the rise in the extent of the vapour phase penetrating the pores of the pressed sample as the ambient pressure increases. However, at a higher pressure the gas formation is suppressed, and the melt formed in the combustion process can selectively wet the pores resulting in inhibition of reaction. Burning rates of mechanical activated system Al+MoO3 are two times higher then not-activated system at ambient pressure ~10 atm and 8 times higher at ~40 atm. In additional experiments, nano-scale MoO3 powder was prepared by evaporation with a subsequent condensation onto cooled plate in an inert-gas fow. Scanning electron microscopy showed that nano-MoO3 particles are absolutely spherical with mean diameter ~100 nm, and atomic-force microscopy 278 D. Meerov et al. reveals smaller particles with mean diameter ~5-30 nm. DSC/TG data showed that the nano-MoO3 starts to sublime earlier than micro MoO3. The use of nano-sized components could considerably increase the burning rates of energetic condensed systems, because of its large specifc surface, lower temperature of sublimation, and high reaction ability.
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Bibliogr. 5 poz.
  • Semenov Institute of Chemical Physics Russian Academy of Science, Kosygin St. 4, 119991 Moscow, Russia,
  • [1] Manelis G.B., Nazin G.M., Rubtsov Yu.I., Strunin V.A., Thermal decomposition and combustion of explosives and powders, Nauka, Moscow 1996, p. 223.
  • [2] Patel D.L., Briggs B.D., Tulis A.J., Austing J.L., Dihu R., Snelson A., Chemical System for In-Situ Neutralization of Landmines in Peacetime, Proc. of the Tech. and Mine Problem Symposium, Monterey, CA, USA, 1996, pp. 6.61-6.66.
  • [3] Umbrajkar S., Hoffmann V., Dreizin E., Aluminum-Rich Al-MoO3 Nanocomposite Powders Prepared by Arrested Reactive Milling, Journal of Propulsion and Power, 2008, 24 (2), 192-198.
  • [4] Schoenitz M., Trunov M.A., Hoffmann V.K., Dreizin E.L., Reactive Nanocomposite Materials Produced by Arrested Reactive Milling, The Proceedings of the International Autumn Seminar on Propellants, Explosives and Pyrotechnics Theory and Practice of Energetic Materials, China, October 23-26, 2007.
  • [5] Umbrajkar S.,Dreizin E.L., Kinetic Analysis of Thermite Reactions in Al–MoO3 Nanocomposites, Journal of Propulsion and Power, 2007, 23(4), 683.
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