Effects of Gas Generation on Nano-Al Fueled Energetic Materials

The reactions of two nano-thermites, aluminum (Al) with copper oxide (CuO) and Al with nickel oxide (NiO) are studied. These oxidizers were selected based on their predicted properties: similar flame temperatures but significantly opposing gas generation. Thermal equilibrium calculations predict that Al+CuO will have a high gas output and the Al+NiO will produce little gas. Flame propagation rates and peak pressure measurements were taken for both composites at various equivalence ratios using an instrumented flame tube. Results show that the Al+CuO had approximately twice the propagation rate and peak pressure of the Al+NiO. A DSC/TGA was used to determine the properties of the composites and reactants under low heating rates. Results indicate that under slow heating both composites experience almost no mass loss. The results suggest that the melt-dispersion mechanism, which is only engaged at high heating rates, leads to a dispersion of high velocity molten Al clusters that promotes a pressure build-up by inducing a bulk movement of fluid. This mechanism may promote convection without the need for additional gas generation.