Recent trends in nanothermites: Fabrication, characteristics and applications

Energetic materials (EMs) are a group of distinctive materials that release an enormous amount of amassed chemical energy in a short time when incited by external mechanical or thermal factors. They comprise of propellants, explosives, and pyrotechnics. Unlike conventional micro-energetic materials, nano energetic materials (nEMs), due to their smaller particle size ranging from 1-100 nm, exhibit higher specific surface area (similar to 10-50 m(2) g(-1)), reduced ignition temperatures from 2350 Kto approx.1000 Kfor particle size from 100 mu m to 100 nmrespectively, higher energy densities (up to 50 MJ kg(-1)), burning rates similar to 30.48 mm s(-1) at 6.894 kPa with specific impulses up to 542 s (5320 ms(-1)), low impact sensitivity (<4-35 J). Such exceptional properties of nano energetic composites, i.e., thermites (a combination of metal-fuel/metal oxide particles), find applications, namely in, munitions, pyrotechnics, energetic micro-electromechanical system (MEMS) chips. This review provides valuable insight into the synthesis methods of nano energetic composite systems (e.g., Al/CuO, Al/KMnO4, Al/Fe2O3, Al/SnO2, Silicon-based systems), their characteristic properties, behavior under certain conditions and applications. Furthermore, the review converses about the advancements made in the last few decades by many researchers, along with the technological gaps that need to be addressed for futuristic applications.