ABSTRACT
During the past decade, a significant research effort has been made to understand the reactivity of elemental nanopowders, such as aluminum, boron, silicon, and several transition metals with different oxidizers. The research effort has also been on investigation of these fuel particles as an energetic enhancement of secondary energetic systems. Energetic materials are a subclass of reactive materials containing both fuel and oxidizer. These materials can be further classified as homogeneous or heterogeneous systems, depending on whether the oxidizer is chemically or physically linked to the fuel. These types of energetic materials are commonly used as propellants, explosives, or pyrotechnics. Homogeneous energetic materials are based on monomolecular compounds, such as TNT, RDX, HMX, and CL-20 (Dreizin 2009). The maximum energy released by these compounds during the combustion process is 50%–500% lower than the energy generated by the combustion of elemental reactants. For example, the oxidation of aluminum or boron generates approximately 30 kJ/g or 58 kJ/g, respectively, compared to 10 kJ/g for HMX energetic material. In order to take advantage of the large energy associated with the oxidation of elemental powders in energetic systems, it is necessary to increase the combustion front velocity by two to three orders of magnitude. Traditionally used micron-sized powders in thermite mixtures are characterized by very low combustion front velocities, only a few 134meters per second. Therefore, efforts to reduce the average particle size of a fuel reactant are necessary to obtain much faster reaction rates.
