Preparation and fire extinguishing mechanism of core-shell solid-liquid composite powder containing ammonium dihydrogen phosphate

A solid-liquid composite powder containing core-shell structure is created under the guidance of theoretical level. Among them, the factors affecting preparation are attributed to stirring speed, solid-liquid mass ratio, stirring time and additive concentration. The results of reduced-size fire chamber indicate that the core-shell structured powder containing NH4H2PO4 (WS-2) can suppress diesel flame more effectively than commercial dry powder (CDP) and common core-shell structured powder (WS-1). Besides, WS-2 shows the highest degree of temperature drop, which is 21.14% and 39.82% higher than CDP and WS-1, respectively. Combined with the results of Thermogravimetric analyzer (TGA) and Fourier transform infrared absorption spectroscopy (FTIR), it can be inferred that WS-2 fully embodies multiple inhibitory effects such as isolation, cooling, asphyxiation and chemical suppression. Ultimately, the excellent fire extinguishing performance brought by its unique structure is demonstrated. This study is of great significance for the determination of technological parameters and appli-cation of core-shell powders.