On the Mechanism of Combustion of Thin Nanostructurized Silicon Plates in Oxygen at an Elevated Pressure

The physical mechanism of combustion of thin nanostructurized silicon plates in oxygen at an elevated pressure is considered. Based on the analysis of experimental data, it has been established that in combustion wave propagation over a nanostructurized silicon film, the liquid silicon droplets resulting from thermochemical destruction of etched silicon undergo combustion, and that the dominant process is the process of heterogeneous combustion of a gas suspension of silicon particles in oxygen. A physicochemical model is presented that describes the speed of combustion wave front propagation in a gas suspension of silicon particles in a liquid phase depending of the oxygen pressure and silicon particle diameter. Dependences of the combustion front speed and of the time of particle combustion on oxygen pressure and size of particles in a gas suspension have been calculated. It has been established that combustion of silicon particles follows the kinetic mechanism with inverse dependence of combustion time on pressure and its proportional dependence on the particle diameter. The dependence of the degree of fragmentation of particles in the combustion wave front on the structure of a nanostructurized sample and oxygen pressure has been calculated. Practically important recommendations for obtaining higher rates of combustion of nanostructurized silicon films at a lower oxygen pressure have been formulated.