Tianjiao Zhang, Xinrui Shi, Run Xia, Xingqiang Tian, Junjiang He
In this study, three kinds of expandable phosphorus-boron composite suppressants (EPBS) were prepared based on ammonium polyphosphate (APP) through coupling agent modification and mechanochemical compounding technology. Through a systematic comparative study on the suppression effects of three EPBS on Al dust explosion, the formulation with the optimal suppression effect was selected. This top-performing EPBS exhibited an initial decomposition temperature of 75 °C, a unit heat absorption capacity of 698 J/g, and the physical coating layer can expand up to 520 times in volume when covering combustible media. As the concentration of EPBS increased, the maximum explosion pressure ( P max ), maximum explosion pressure rise rate ((d P /dt) max ), and average flame propagation velocity ( V avg ) all decreased. Additionally, the critical suppression concentration was further reduced to 400 g/m 3 , eliminating the phenomenon of enhanced explosion intensity (SEEP). EPBS exerted the suppression effect through chemical and physical mechanism (heat absorption, coating, barrier formation and dilution). Chemically, the decomposition products of EPBS capture key explosion radicals O and AlO through radical-scavenging reactions (HOPO + O<=>OH + PO 2 , HPO 3 +O<=>OH + PO 3 ), thereby interrupting the chain reaction pathway of Al dust combustion in the gas phase.