Preparation and characterization of granular hybrid reactive materials

The feasibility of preparing granular hybrid reactive materials (GHRM) comprised of an Al matrix and micrometer-sized nanocomposite thermite inclusions using in situ consolidation by mechanical milling is established. The starting components were Al and nanocomposite Al-CuO and Al-MoO₃ thermite powders with various specific compositions. The nanocomposite powders were prepared using arrested reactive milling. Both shaker and planetary mills were successfully used to prepare samples of GHRM particles with sizes ranging from approximately 0.1 to 1 mm. Prepared particles were size classified and characterized by electron microscopy and x-ray diffraction. Specifically*the effects of milling conditions and compositions on the particle size distributions*mixing uniformity*and structures of the prepared hybrid particles were studied. A continuous CO₂ laser was used to ignite the hybrid particles in air. Combustion emission was recorded using a photodiode and the experiments were visualized using high-speed video records. It was observed that the ignition delays are much shorter for GHRM particles when compared to similarly sized Al. The optical emission produced by burning GHRM particles is substantially stronger than that for similarly sized Al*and unlike for Al particles*GHRM particle combustion is accompanied by multiple fragmentation events. Combustion times for GHRM particles are much shorter than for similarly sized Al. Once ignited by the laser beam*combustion of GHRM particles continues if a suitable oxidizer is present.