Highly Insensitive/Reactive Thermite Prepared from Cr₂O₃ Nanoparticles

Abstract

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 (Cr2O3) as function of the oxide particle size. Homogeneous composites were prepared by mixing Al nanoparticles (Φ≈50 nm) with Cr2O3 micro‐ and nanoparticles (Φ≈20 nm), respectively, in hexane solution. The dried Cr2O3/Al composite powders were ignited by using a CO2 laser beam. The use of nanosized Cr2O3 particles incontestably improves the energetic performances of the Al/Cr2O3 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 Cr2O3 is two orders of magnitude lower than the thermite prepared from other metal oxide nanoparticles (MnO2, WO3). Finally, our study shows that the decrease of Cr2O3 particle size has an interesting and beneficial effect on the energetic properties of Cr2O3/Al thermites and appears as an alternative to tune the properties of these energetic materials.

Safer and Performing Energetic Materials Based on Polyaniline-Doped Nanocomposites

“…Different profiles can be divided into three and four zones for the Al/WO3 and the Al/WO3/PAni_LF composites, respectively. The combustion regimes are multistage, and based on our experience and knowledge [18,[32][33], an attempt to Finally, note that the combustion velocity of the PAni-doped nanothermites is of the same order of magnitude as that of the conventional binary Al/WO3 nanothermite. This result represents a truly major scientific breakthrough in the preparation of safer and more reliable reactive nanocomposites because the studies conducted for desensitising energetic nanocomposites and reported in the literature have always led to a drastic loss of reactivity [16,18].…”

Visible‐Light‐Driven Plasmonic Photocatalysis Enhanced by Charge Accumulation

“…XRD patterns of CrO x were also measured on glass substrates to avoid signal overlapping with FTO. Although the ∼30 nm thick film shows weak signals, the ∼300 nm thick layer shows discrete peaks, most of which are attributed to Cr 2 O 3 (Figure c) . A weak signal at ∼31° is probably ascribed to CrO 3 , suggesting a coexistence of Cr 3+ and Cr 6+ .…”

Nanothermites: A short Review. Factsheet for Experimenters, Present and Future Challenges

“…Nanothermites and their derivatives can be also used as fast burning compositions for short pyrotechnics delays [109], with time bases ranging from milliseconds to microseconds per centimeter. The slowest fast delay systems could be prepared from gasless nanothermites such as Al/ Cr 2 O 3 [110,111], Al/NiO [112], or red P/Fe 2 O 3 [113]. The velocity can be adjusted by playing on the composition, the particle size of components and the density of mixtures.…”