Mesoporous Hydrophobic Silica Nanoparticles as Flow-Enhancing Additives for Fire and Explosion Suppression Formulations

This paper describes a fire and explosion suppression formulation with increased flowability that ensures fast operation and high efficiency of an active explosion suppression system (complete fire and explosion suppression time = 2.25 ms; spraying capacity = over 98%). For the first time, the possibility of using mesoporous materials of different structures (MCM-41, MCM-48, and SBA-15) with high specific surface area as flow additives for these formulations has been reported. This also covers the results of an experimental study on the influence of various mesoporous silica materials used as additives on the rheological characteristics of a monoammonium phosphate (MAP)-based fire and explosion suppressant. Particular attention is paid to analysis of the results of the experiments in which the mesoporous materials are protected from moisture via poly(methylhydrosiloxane) hydrophobic modification. The study of the rheology of powders indicates that the flow parameters depend on the surface characteristics of silica nanoparticles and their size and concentration. The incorporation of superhydrophobized silica into MAP leads to a decrease in the cohesion force and an increase in the flow function ff (composition contact angle > 163 degrees). The amount of superhydrophobic silica also affects the autoadhesion forces between particles. It has been established that the minimum resistance of a fire and explosion suppression powder to the flow occurs when modified nanoparticles with SBA-15-type structure are used as additives. The efficiency of hydrophobized silica materials as additives increases greatly with a decrease in the size of their particle agglomerates. The joint use of SBA-15 and Aerosil 380 silicas makes it possible to improve the rheological properties of the fire and explosion suppression formulation and to significantly increase its flowability.