Propellants Explosives Pyrotechnics, Vol.43, No.11, 1178-1183, 2018
Combustion of Magnesium-Sulfur Composite Particles Ignited by Different Stimuli
Composite Mg center dot S powders were prepared by mechanical milling. Magnesium powders coated with sulfur were prepared by soft milling using glass beads as milling media. Three-dimensional composite powders, in which magnesium and sulfur were mixed on the nanoscale were prepared by milling using steel balls as milling media. Both composite powders were explored in two ignition experiments. In one case, monolayers of the prepared powders were exposed to electrostatic discharge (ESD). In the other case, powder particles were fed through a focused CO2 laser beam. In both experiments, emission traces produced by burning particles were captured using a filtered photomultiplier tube; the data were processed to recover respective combustion times. Combustion products were collected and examined using electron microscopy for the ESD-ignition experiments. It was found that the burn times of the sulfur coated magnesium powders were shorter than those of three-dimensional composites in both experiments. No effect of ignition method on burn times was observed for the sulfur-coated powders. For three-dimensional composite powder, burn times of ESD-ignited particles were shorter than those for particles ignited by passing through the CO2 laser beam. Analysis of the captured combustion products suggests that magnesium and sulfur are readily separated upon heating for the coated powders, but not for the three-dimensional composites. For the latter case, the reaction is dominated by MgS formation, while for the former case, it is primarily magnesium oxidation in air.