Insight to hydrophobic SiO2 encapsulated SiO2 gel: Preparation and application in fire extinguishing

Highlights: • A new capsule encapsulating material has been successfully fabricated. • Multiple good features reflect the excellent performance of HSESG. • HESEG excels in extinguishing wood stack fire than ABC dry powder. Micron-sized hydrophobic SiO₂ encapsulated SiO₂ gel (HSESG) was prepared successfully by using SiO₂ gel as the solid core and hydrophobic nano-SiO₂ particle as the shell under high-speed shear stirring. The flowability, stability, particle size distribution, bulk density and water repellency of the powder were measured separately, and it was concluded that this type of product can exhibit smaller static angle, larger flow rate and lower bulk density. After the formation of a stable spatial network of SiO₂ gel in its interior, relevant fire extinguishing experiments were carried out and HSESG exhibits higher efficiency in suppressing wood stack fires than that of ordinary dry water (DW) and ABC dry powder. As a high-efficiency fire-extinguishing material, it also exhibits excellent environmental friendliness and non-toxicity, which will make it have the potential to develop a new application market.