Study on Indium (III) Oxide/Aluminum Thermite Energetic Composites

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.

Conductive Oxides for Formulating Mitigated-Sensitivity Energetic Composite Materials

“…With regard to the friction sensitivity, the Al/ITO formulations were moderately sensitive to insensitive (≥324 N). This is common for energetic formulations, such as Al/In 2 O 3 , Al/SnO 2 , and Al/Nb 2 O 5 , but better than Al/WO 3 , Al/MnO 2 , Al/Bi 2 O 3 , and Al/CuO composites whose thresholds are <5 N (for the first three listed) and 9 N, respectively [13,16,[34][35][36][37]. With respect to the spark sensitivity, Al/ITO materials showed a similar trend compared to the Al/In 2 O 3 system, with a high sensitivity at the nanoscale (like many binary energetic compositions reported in the literature) and a mitigation of the ESD sensitivity when oxidizing microparticles are involved.…”