Boron-based composite energetic materials (B-CEMs): Preparation, combustion and applications

Metal fuels are attractive for solid/hybrid rocket propulsion and energy-conversion applications, because of their high energy densities. Boron powder (B), due to its high gravimetric (58.30 MJ·kg−1) and volumetric heats of combustion (136.44 kJ·cm−3), is ideally one of the most promising fuel candidates for fuel-rich solid propellant (SP). However, from an application perspective, amorphous B has drawbacks of high ignition temperatures and incomplete combustion, resulting in low energy-release rate and efficiency. Thus, there is growing interest in employing B-based composite energetic materials (B-CEMs) in SP, explosives, and pyrotechnics. The present work provides a comprehensive review of the advances made over the past few decades in the areas of preparation, combustion, and applications of B-CEMs. The preparation methods of various types of B-CEMs are introduced, and the physicochemical properties of B-CEMs are systematically discussed particularly with regards to achieving advantages over B and other metal powders in a broad range of applications. The ignition and combustion behavior of different energetic formulations with B-CEMs are reviewed. Finally, the existing problems and future challenges in our understanding of the field (prospects) are discussed.