Abstract

In the search for new high performance energetic compositions, nanosized and ultra-fine powders have been identified as promising components of solid propellants, pyrotechnics, and explosives. Sensitivity and performance of composite energetic materials are both affected by the size and morphology as well as the distribution of the individual components. Since reaction kinetics depend on mass transport rates between the reactants, increased interface area between the components leads to increased performance of nanosized or nanostructured materials.

Recently, arrested reactive milling (ARM) has been used to prepare a number of nanostructured composites of thermite systems, such as Al-MoO₃, Al-Fe₂O₃, or Al-CuO. For ARM synthesis, the reactants are ball-milled, and the milling process is interrupted before a spontaneous reaction is mechanically triggered. Prolonged milling leads to the formation of composite particles with increasingly refined structure. The milling time at which the reaction is mechanically triggered effectively sets a limit to the achievable degree of refinement. This time limit can be influenced by the specific milling parameters chosen, such as the amount of sample, the ratio of sample to milling media, and the use of process control agents. Under appropriate conditions, nanoscale composite particles can be synthesized.

In order to make efficient use of these types of material in energetic applications, ignition and reaction behavior and therefore the reaction mechanism between the reactants must be known. This research explores the reaction mechanism in an Al-CuO nanocomposite powder prepared by arrested reactive milling.

The methodology of present research here uses thermal analysis and x-ray diffraction to determine at what temperatures reactions occur, and what phases are involved in these reactions.