Combustion of Silicon in Pressurized Oxygen

In pyrotechnic applications, silicon particles oxidise in confinement under high pressure. Phenomenological studies on the burning behaviour of silicon particles in
oxygen at 0.1 to 4 MPa are performed at the ICT window bomb with macro high-speed images, emission spectroscopy and residue characterisation with SEM/EDX. In addition to reactions in the gas phase, such as the formation of SiO and rapid condensation to form fine fumed silica, intensive heterogeneous reactions between melt and gas are observed inside the molten phase with bubble formation and eruptions of spherical particles. The phenomena show a strong pressure dependence. The observations are discussed using the thermodynamic equilibrium for the formation of gaseous silicon monoxide.