Oxidation, ignition and combustion of Al-hydrocarbon composite reactive powders

Metal fuel additives are used in advanced explosive formulations to achieve higher combustion temperatures and longer pressure pulses. Cryomilling is used to prepare Al-based reactive composites to replace pure Al as a fuel additive in explosives for multiple applications. In this project, Al-paraffin wax and Al-polyethylene composite materials were prepared and characterized. The prepared powders were initially evaluated using thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. Ignition temperatures of the prepared materials were determined at heating rates varied in the range of 2000-23000 K/s using an electrically heated filament. Materials were burned as individual particles and as aerosolized clouds. Ignition temperatures were significantly lower for all composite materials compared to pure Al. Single particle burn times were longer and combustion temperatures were comparable to those of pure Al powders. Combustion dynamics of the composite material particles was affected by the hydrocarbon additives retained in the material after its ignition despite the very high combustion temperatures. In aerosol combustion tests, the pressure for Al-hydrocarbon composites was negatively affected by strong agglomeration of the partially burned particles.