Boron as Fuel for Ceramic Thermites

• DOI: 10.1021/ef500221p
• Publication Date: 2014-05-19T04:51:03Z
• Authors: Marc Comet; Fabien Schnell; Vincent Pichot; Julien Mory; Benedikt Risse; Denis Spitzer
• Keywords: Boron oxide; Bismuth

Boron submicrometer particles (22.3 m2/g) were used as fuel to prepare energetic compositions with bismuth(III) oxide (2.7 and copper(II) (10.7 m2/g), leading unconventional submicrometer-thermites being made solely of ceramic compounds. The morphology the mixtures was studied according their boron content: (i) by comparing calculated apparent density experimental one (ii) a photometric technique based on analysis gray levels samples. early step reaction, corresponding preignition exotherm observed in DSC experiments, has shown that is first reduced Bi2O3 molten bismuth layer at surface particles. dissolution this metallic coating favors reaction. Conversely, B2O3 formed oxidation further reacts Bi2O3, forming glass like limits diffusion Bi2O3. reaction decelerated phenomenon requires higher temperature reach completion (second exotherm). This mechanism accounts for incomplete Bi2O3/B compositions. nature crystallized phases present combustion residues identified X-ray diffraction (XRD) correlated evolution heat measured calorimetry. For both (Bi2O3/B CuO/B), remains high level over wide composition range. result explained formation different oxides (B2O3, B7O). Boron-based thermites are relatively insensitive friction impact but possess extremely low sensitivity electrostatic discharge ignite quite easily contact an open flame. investigation ejection rate reactive power boron-based nanothermites 2 orders magnitude less than aluminum counterparts. Because moderate reactivity, promising candidate materials ignition devices specific propulsion applications.