The self-ignition of the boron particles gas suspension with an oxide-free surface

The paper presents an analysis of the current state of the issue of ignition of dispersed boron systems, as one of the promising components of solid rocket fuels. It was found that the main, limiting role in slowing down the ignition of a gas suspension of boron particles is played by the stage of oxygen diffusion through the film of boron trioxide B2O3 on the surface of boron particles. Various known methods (thermal, chemical) of intensification of the ignition process are considered in detail and a new method is proposed, which involves organizing the process directly on the surface of the particles free from B2O3. The results of calculations of the critical ignition temperature of a monodisperse gas suspension of boron particles with d0=0.2 μm without an initial oxide coating in heated air at normal atmospheric pressure are presented. A scheme for implementing an experimental method for determining the ignition temperature of a gas suspension of solid fuel particles with the possibility of varying the volumetric concentration of the latter is proposed. The obtained experimental data confirm the effect of a significant decrease in the critical ignition temperature of a gas suspension of boron particles, if the process is organized so that during the reaction on the surface of the particles, instead of liquid boron trioxide B2O3, gas-phase dioxide B2O2 is formed, and are satisfactorily consistent with the results of calculations based on the ignition model of boron particles without an initial oxide film.