(701e) The Effect of Particle Morphology On the Combustion Properties of MIC Materials

In recent years, the main focus of research in the area of Metastable Intermolecular Composite (MIC) materials has been focused on the use of different nano-scale reactants in order to modify combustion characteristics of such nano-scale materials. By decreasing the particle size of the fuel and oxidizer from micron to nano scale the combustion velocity can be increase from a few meters to tens or hundreds of meters per second depending on the MIC material. During the past decade, the main focus was on use of aluminum nanoparticles mixed with different metal oxides, such as molybdenum trioxide, bismuth trioxide, copper oxide, and iron oxide. The cost of 80 nm spherical aluminum powder is rather very high and its market availability is limited. The 80 nm aluminum has a surface area in a range of 22-24 m²/g and a reactive aluminum content of approximately 76%. An alternative route of the formation of aluminum with the similar surface area and the reactive aluminum content has been investigated at the South Dakota School of Mines and Technology. This nano-size aluminum with a flake like structure has been formed by attrition milling. The effect of key milling parameters on the ultimate properties of nano-flakes will be discussed. Tests have shown the nano-flake aluminum is less sensitive to ESD (electrostatic discharge) than spherical powder having similar specific surface area and the reactive aluminum content. In addition, the comparison of basic combustion characteristics such as, recoil force, pressure generation, and combustion velocities, for nanothermites based on spherical and flake-like nanoaluminum mixed with Bi₂O₃ or Fe₂O₃ will be discussed.