Energetic advantages of aluminum nanopowders passivated by active coatings

Al nanopowders (ANP) produced by plasma electrical explosion method possess an increased reactivity at oxidation processes and during combustion in comparison with other ANP's, produced by equilibrium methods (evaporationcondensation, chemical and thermal destruction of precursors, mechanochemistry etc.). It is known that a nature of such a high reactivity for ANP is connected with their structural features (widening of the crystal lattice, very thin passivating films (thickness about 2 nm) of oxides and other passivating reagents on metallic particles with a diameter 100 nm) and also dimensional factors (high energy of the surface: S = 10-20 m2/g). The use of electroexplosive ANP in different propellants is widely studied: it was shown that agglomeration of particles by combustion is reduced in the case of ANP, combustion rate of compositions increases, whereas two-phase losses and pressure exponent in the burning law are reduced. A thermodynamic analysis of improvement ANP properties, i.e. passivation by non-inert materials (not Al2O3) was studied. It is shown that the most advanced characteristics has the powders passivated by nitrocellulose, but the sensitivity for such nanopowder is also higher. The experiments of different coatings application on the surface of ANP were also carried out. The most advanced coatings were made from nitrocellulose, boron, aluminum nitride, ADN and srearic acid. The work is supported by INTAS (Project YSF 03-55-671) and RFBR grant (04-02-16503-a)