Short Term Innovative Research Program: Nanoengineered Reactive Materials for Tunable Ignition and Energy Release

摘要

Most conventional explosives can be roughly categorized into two classes - molecular materials and intermolecular composites. Molecular materials refer to species such as the nitroalkanes (e.g. nitromethane) and cyclic nitramines (e.g. TNAZ, RDX, HMX) that release chemical energy primarily by converting singly bonded nitrogen to more stable doubly and triply bonded forms. Intermolecular composites release chemical energy by anion exchange between the composite phases and the formation of new and more thermodynamically stable compounds. Traditionally, molecular materials have been the premier energetic compounds because they can store relatively large amounts of energy (in the range of 4 kJ/cc), they can be rapidly ignited by mechanical shock to produce high power, the products of reaction are superheated gases that do work on their surroundings, and they can be mass produced. In contrast, intermolecular composites (typified by one of the oldest energetic materials: black powder) store substantially more chemical energy, up to 25 kJ/cc, but the ignition mechanisms are most commonly thermal. Consequently, the energy release is regulated by diffusion, and although their reactions can produce temperatures in excess of 2000 degrees Celsius, the relatively slow resulting kinetics dramatically limits power output.