The modification of thermochemical parameters of aluminum nanopowder after irradiation by accelerated electron beam

In the course of conversion metals into nanodisperse state the emergence of new nanopowders properties was observed, including the energy storage by nanopowders. Herewith, the energy stored is related to nanoparticles surface energy, as well as the energy may be stored in their structure. The energy stored in a surface is limited by nanoparticle stability. If the particle diameter is less than 30 nm, it cannot be stabilized in the air. An assumption about the existence of double electric layer which has a pseudocapacity was made based on the results of experiment in which there was a protective film thickness reducing by particle size decreasing. The interest in aluminum powders and nanopowders is growing due to their usage as sintering aids in the powder metallurgy, as high-energy additives in propellants and pyrotechnics mixtures. Furthermore, the development and spreading of 3D printing technologies requires the creation ofpowder materials capable of sintering at low heating energy and for a short period of time. One ofpossible solutions to this problem is to irradiate powder materials with high-flow of electrons, which leads to energy storage in nanopowder. The aim of this work was to establish the accelerated electron beam irradiation effect patterns on the quantity of aluminum nanopowder stored energy and other oxidation parameters of the aluminum nanopowder. It was found that the oxidation starts at the temperature in the range from 410 to 460°C and independent on the radiation dose. The degree of oxidation varied from 44.4 to 58.3% and its dependence on the radiation dose was not established. The heat energy release occurred in two stages: at the first stage (up to ~ 660° C) in general the increase of the thermal effect was observed. At the second oxidation stage of irradiated aluminum nanopowder the growth of the thermal effect also observed. The peak of heat effect achieved by irradiation (45.0 kGy absorbed dose) was 2576 J/g higher than the thermal effect for non-irradiated aluminum nanopowder. This quantity is 6 times greater than the standard aluminum melting heat (400 J/g).

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