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1 Central European Journal of Energetic Materials

1 2007

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Investigation of Al Nanopowders Produced by the Exploding Wire Method

Sedoi V., Osmonaliev M., Chemezova L., Volkova G., Ivanov V., Alekseev A.

Central European Journal of Energetic Materials

2007

Vol. 4, nr 1-2

17-30

The impetus for this research came from fundamental and applied questions connected with specified characteristics of Al nanopowders, theirs controlled syntheses and passivation, and their activity as high energetic ingredients in solid propulsion and in aluminum-water gels. Different conditions of powder syntheses by the exploding wire method and powder passivation were used: syntheses at low-pressure gases (Ar, N2, CO2) and passivation in atmospheric-pressure gases (air, N2, CO2). Investigations of particle sizes and morphology have been accomplished with a 125-kV transmission electron microscope. The specific surface area S has been determined by BET method. Particles are predominately spherical, BET surface area was of 15-40 m2/g. The composition and surface properties of nanopowders produced under various conditions were studied by mass-spectroscopy techniques at temperatures of 0-450 C, by electron and X-ray diffraction methods, and by elemental analysis methods. To determine activities of the powder samples in the combustion reactions, the Differential Thermal Analysis, Thermogravimetry, and reaction with water were conducted. Active metal contents have been determined from amount of impurities and hydrogen extracted in direct thermohydrolysis of nanopowders by distilled water at 60 C. Kinetics of gas evolution was determined therewith and shows two steps. Active aluminum content is within range of 16-80%. A composition of adsorbed gases and dynamics of desorption in vacuum have been investigated too. Correlation between conditions of nanopowder syntheses and specific surface and chemical activity in reaction with water and maximum oxidation degree have been determined. Keywords: nanopowders, characterization, passivation, oxidation, combustion