Spherical solid fuel particles combining boron and polytetrafluoroethylene

This work is aimed to develop improved boron-based fuels capable of taking the full advantage of its high theoretical volumetric and gravimetric heats of combustion. Emulsion-assisted milling (EAM) was used to prepare spherical composite powders combining boron with 1 – 10 % polytetrafluoroethylene (PTFE) with particle sizes close to 10 µm. Different characteristics of the prepared powders were compared to those of the commercial boron serving as the starting material. The tapped density of the prepared spherical powders was much greater than that of starting boron indicating an improved flowability. The thermally activated oxidation for the spherical powders started at lower temperatures than for the starting boron. The intensity of the low-temperature reactions increased with an increased concentration of PTFE. The accelerated low-temperature oxidation correlated with reduced ignition temperatures measured for the composite powders coated on an electrically heated filament. In constant volume explosion experiments, substantially greater maximum pressures were measured for the spherical composite powders compared to the starting boron. The results suggest that the powder morphology tunable via the EAM plays the major role in improving its reactivity. The effect of the added PTFE is non-negligible but appears to be secondary.