Nanoscale heat transfer effects in the combustion of nanoenergetic materials

Metal-based composite energetic materials have substantially higher volumetric energy density when compared with monomolecular compounds such as trinitrotoluene (TNT). Micron-sized metal particles have been routinely used for energetic applications since the 1950’s. They, however, suffer from several drawbacks such as high ignition temperatures, agglomeration, and low reaction rates, resulting in low energy release rates. Nanoparticles exhibit beneficial physicochemical properties compared to their micron-scale counterparts for combustion applications. Due to the large specific surface area (SSA), they also offer tailorable surface properties that have the potential to allow precision control of thermal transport and chemical kinetics. Hence, during the mid-1990’s, widespread replacement of microparticles with nanoparticles created a new class of energetic materials called nanoenergetic materials. Among the different candidate metals, aluminum is desired because of its abundance, high oxidation enthalpy, low cost of extraction, and for its relatively safe combustion products. This study provides a perspective to combustion wave propagation in nano-energetic materials that accounts for nanoscale heat conduction effects. Here we use the nano-aluminum – water system as an example system. A fundamental treatment of heat transport in nanoparticles and interfaces is carried out. Firstly, ab initio and atomistic scale simulations were performed to investigate the nanoscopic nature of heat transport in bulk and nanosized aluminum and aluminum oxide, as well as at the interface of these materials. Atomistically informed macroscale modeling techniques were then employed to treat heat transport in mixtures of nanoparticles in liquid oxidizer to study combustion wave propagation.Ph.D