In‐Flight Synthesis of Core–Shell Mg/Si–SiO_x Particles with Greatly Reduced Ignition Temperature

Abstract Magnesium is a promising candidate as a solid fuel for energetic applications, however, the diffusion‐controlled oxidation mechanism impedes its reaction with an oxidizer, often resulting in diminished performance. In this study, non‐thermal plasma processing is implemented to modify the surface of magnesium nanoparticles with silicon in‐flight, in the gas‐phase to enhance the rate of interfacial reactions and tune the ignition pathways. Allowing the silicon coating to partially oxidize provides direct contact between the fuel and oxidizer, resulting in a nanostructured thermite system at the single particle level. The proximal distance between oxidizer and fuel directly impacts the ignition temperature and, therefore, the combustion kinetics. An intermetallic reaction occurs within the magnesium/silicon system to supplement the heating of the magnesium fuel to initiate its reaction with the oxidizer, resulting in highly reduced ignition thresholds. The ignition temperature is lowered significantly from ≈740 °C for magnesium particles with a native oxide layer to ≈520 °C for particles coated via the in‐flight plasma process.