Abstract
Thermites or composite energetic materials are mixtures made of fuel and oxidizer particles at micron-scale. Thermite reactions are characterized by high adiabatic flame temperatures (>1000 °C) and high heats of reaction (>kJ/cm3), sometimes combined with gas generation. These properties strongly depend on the chemical nature of the couple of components implemented. The present work focuses on the use of indium (III) oxide nanoparticles as oxidizer in the elaboration of nanothermites. Mixed with an aluminum nanopowder, heat of reaction of the resulting Al/In2O3 energetic nanocomposite was calculated and its reactive performance (sensitivity thresholds regarding different stimuli (impact, friction, and electrostatic discharge) and combustion velocity examined. The Al/In2O3 nanothermite, whose heat of reaction was determined of about 11.75 kJ/cm3, was defined as insensitive and moderately sensitive to impact and friction stimuli and extreme sensitive to spark with values >100 N, 324 N, and 0.31 mJ, respectively. The spark sensitivity was decreased by increasing In2O3 oxidizer (27.71 mJ). The combustion speed in confined geometries experiments was established near 500 m/s. The nature of the oxidizer implemented herein within a thermite formulation is reported for the first time.
Highlights
Thermites are described as highly exothermic reactions between a reducing metal and an oxide ceramic to form a more stable oxide associated with the metal derived from the original ceramic
This investigation demonstrates the successful use of indium (III) oxide ceramic (In2 O3 ) as an oxidizer in metastable intermolecular composites
This was achieved by mixing In2 O3 material with an aluminum nanopowder under stoichiometric conditions
Summary
Thermites are described as highly exothermic reactions between a reducing metal and an oxide ceramic (both at the micron scale) to form a more stable oxide associated with the metal derived from the original ceramic An illustration of this kind energetic mixture is the reaction (1) involving aluminum and iron (II, III) oxide for welding railway rails [1]. Over the past two decades these composite materials have attracted growing interest in pyrotechnics, with the elaboration of systems using nanoscale components to form what researchers call metastable intermolecular composites (MICs) or nanothermites These energetic nano-systems have the advantage, on their micron scale counterparts, of reducing ignition delays (up to three order of magnitude) and increasing combustion speeds (
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