Manufacturing, Properties, and Application of Nanosized Superhydrophobic Spherical Silicon Dioxide Particles as a Functional Additive to Fire Extinguishing Powders

Abstract

The method of manufacturing nanosized spherical superhydrophobic silica particles is reported. The efficiency of hydrophobized nanosilica (NS) as an additive to fire extinguishing powders (FEP) based on ammonium phosphates was evaluated. The effect of hydrophobization on the texture properties, size, and shape of the NS additive particles was studied. The surface of the fire extinguishing component is uniformly coated by spherical hydrophobized NS nanoparticles without a high-speed mixing procedure. NS additive provides a highly hydrophobic coating to the particles of the FEP + NS fire extinguishing powder. The apparent contact angle of the coated particles was found to be larger than 160°. The dynamic flow resistance of commercial and FEP + NS fire extinguishing powders was compared. The specific energy and aerated flow energy of the FEP + NS is relatively low, thus indicating a weak aerodynamic interaction between the particles in dynamic processes. It was established that the spraying resistance of FEP + NS is the lowest among the studied fire extinguishing powders (including commercial ones), so it is characterized by the best flowability.

Study on Flowability Enhancement and Performance Testing of Ultrafine Dry Powder Fire Extinguishing Agents Based on Application Requirements

“…Fumed silica was purchased from Shanghai Aladdin Biochemical Technology Co. Ltd. (hydrophobic-120 type), 99.8% metal-based, with a particle size of 7-40 nm and specific surface area of 120 m 2 /g. Perlite, magnesium stearate, and bentonite were selected and used as functional additives to further promote flow in ADP powders, and the optimum ratio for addition was investigated [23]. Perlite was purchased from Lingshou County Woyuan Mineral Products Processing Plant, D 100 ≤ 74 µm.…”

“…In order to develop free-flowing UDPAs, hydrophobic treatment, such as the addition of hydrophobic fumed silica, is first required [23]. Capillary bridges can form between particles in wet UDPAs.…”

“…Hydrophobic additives improve the flow of UDPAs by reducing the friction on the particle surface. Other additives such as metal stearates, perlite, and active white clay, which are common additives in fire extinguishing agents, can also improve the flow characteristics of UDPAs [23]. Optimizing the content of functional additives in UD-PAs is rather challenging.…”

Synthesis of Hydrophobic Nanosized Silicon Dioxide with a Spherical Particle Shape and Its Application in Fire-Extinguishing Powder Compositions Based on Struvite

“…The study [ 12 ] describes a method for the preparation of superhydrophobic mesoporous structures with an application of trifunctional alkoxysilane precursors (methyltrimethoxysilane and methyltriethoxysilane) containing a hydrophobic methyl group. Currently, a large number of works are dedicated to the utilization of modified silica materials as functional additives for powder compositions to improve the flowability of cohesive powders and impart hydrophobic properties to them [ 13 , 14 , 15 , 16 ].…”

“…The negative effect of air humidity can be controlled by creating a dry coating of hydrophobic silica particles [ 15 , 16 ]. On the one hand, a coating of nanosized silicon dioxide particles increases the distance and diminishes the contact area between the particles of powder composition, reducing the surface energy and electrostatic charge [ 13 ]. On the other hand, the coating particles are able to absorb water vapor and prevent the formation of capillary bridges between the components [ 14 ].…”