Highly Insensitive/Reactive Thermite Prepared from Cr 2 O 3 Nanoparticles

• Published in: Propellants, explosives, pyrotechnics explosives, pyrotechnics, 2011-02, Vol.36 (1), p.80-87
• Main Authors: Gibot, Pierre, Comet, Marc, Eichhorn, Alfred, Schnell, Fabien, Muller, Olivier, Ciszek, Fabrice, Boehrer, Yannick, Spitzer, Denis
• Format: Article
• Language: English
• ISSN: 0721-3115; 1521-4087
• DOI: 10.1002/prep.201000080

Thermites prepared from nanoparticles are currently the subject of growing interest due to their increased performances compared to classical micrometer‐sized thermites. Here, we studied the combustion behavior of energetic composite composed of Al and chromium (III) oxide (Cr 2 O 3 ) as function of the oxide particle size. Homogeneous composites were prepared by mixing Al nanoparticles ( Φ ≈50 nm) with Cr 2 O 3 micro‐ and nanoparticles ( Φ ≈20 nm), respectively, in hexane solution. The dried Cr 2 O 3 /Al composite powders were ignited by using a CO 2 laser beam. The use of nanosized Cr 2 O 3 particles incontestably improves the energetic performances of the Al/Cr 2 O 3 thermite since the ignition delay time was shortened by a factor 3.5 (16±2 vs 54±4 ms) and the combustion rate (340±10 mm s −1 ) was significantly accelerated in contrast to those reported until now. Interestingly, the sensitivity to friction of the Al‐based thermites formulated from Cr 2 O 3 is two orders of magnitude lower than the thermite prepared from other metal oxide nanoparticles (MnO 2 , WO 3 ). Finally, our study shows that the decrease of Cr 2 O 3 particle size has an interesting and beneficial effect on the energetic properties of Cr 2 O 3 /Al thermites and appears as an alternative to tune the properties of these energetic materials.