Effects of aluminum addition on flash ignition and combustion of boron nanoparticles

Abstract

Boron has been of considerable interest as fuel for propellants and explosives due to its high gravimetric and volumetric calorific values. In this study, the effects of different mixed modes, blending ratios, and packing densities on ignition and combustion characteristics of boron-aluminum mixture were explored using flash ignition facility and thermobalance. The results showed that the boron nanoparticles can be ignited upon exposure to the flash with a certain amount of aluminum nanoparticles addition and the flame luminous intensity increased with content of the added aluminum. The boron-aluminum mixture in loose contact performed better combustion characteristics than those in tight contact because of more access to the oxygen and less heat dissipation into the bulk sample. The main combustion products were detected and analyzed by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The temperatures of the ignited nanoparticles were measured and mostly distributed between 1273 K and 1473 K. The burning time decreased significantly with the increase of aluminum addition at the high packing density condition. The boron combustion efficiency increased with the addition of aluminum content in loose contact. The thermogravimetric experimental results showed that the aluminum addition could decrease the primary ignition temperature of boron. Moreover, the photothermal effect and plasmon resonance effect of aluminum were the potential flash ignition mechanism of the boron-aluminum mixture.