Consolidation of reactive nanocomposite powders

There is interest in replacing energetically inert structural components with reactive structures capable of highly exothermic reactions. Consolidated reactive materials are also desired for other applications, including reactive fragments, high density additives to explosives, insensitive pyrotechnic components, etc. Unlike nano-energetic compositions based on mixed nanopowders, reactive nanocomposite powders prepared by Arrested Reactive Milling (ARM) can be readily consolidated to achieve combined characteristics of high reactivity, low porosity, and structural strength. Different consolidation methods can be applied, and as a first step, a simple uniaxial pressing of nanocomposite powders is used in this project. A set of reactive nanocomposite powders with several Al-based thermite compositions prepared by ARM was used to prepare pellet-like consolidated samples. For various mechanical tests, both cylindrical and rectangular pellets were prepared with varied dimensions and varied degrees of compaction. Pellet compaction densities exceeding 90% of theoretical maximum density, were achieved. Despite the presence of Al and oxidizers, including MoO₃, CuO, Bi₂O₃ and others, mixed on the nanoscale in different samples, no reaction was observed to be triggered by the powder compaction at pressures reaching 500 MPa. An experimental technique has been developed to study the thermal ignition initiation of the consolidated samples as a function of their physical and mechanical properties. The experimental technique will be used to develop a theoretical model to describe the ignition behavior of the consolidated materials.