Combustion of explosively dispersed Al-Mg-Zr composite particles

Abstract

Micron-sized composite particles consisting of an Al-Mg alloy and Zr were produced via mechanical milling. Three different particle chemistries were prepared with varying ratios of the Al-Mg alloy to Zr. In addition, the prepared powders were size selected using mechanical sieves. Explosively launched combustion properties of these powders were independently measured as a function of the particle stoichiometry and particle size. Ignition temperatures were measured utilizing a heated filament experiment while combustion efficiency was characterized by measuring the dynamic pressure produced in a closed bomb in which the powder was explosively dispersed under fixed enthalpy conditions. Commercial Al powder, Valimet H-2, was also tested alongside these materials as a benchmark. High-speed video and thermocouple measurements were also obtained for the closed bomb experiments. We observed an increase in combustion efficiency from 30% to 80–90% in the composite materials compared to the pure Al. Furthermore, reaction products were collected and analyzed by powder x-ray diffraction to gain further insight into combustion efficiency and reaction pathways. We observed significant improvement of combustion under these experimental conditions, including higher quasi-static pressures and higher rates of pressure rise, with composite fuels compared to pure Al, even without a secondary oxidizer additive.