Suppression efficiency and mechanism of low-temperature phase-transition composite explosion suppressants for MgH2 dust explosions

Magnesium hydride (MgH 2 ) dust poses a higher explosion hazard than metallic Mg because dehydrogenation releases H 2 , which promotes gas-phase chain reactions and flame acceleration. Hydrated salts are promising suppressants for hydrogen-related explosions because their dehydration can absorb heat and release water vapor for dilution. In this study, a SiO 2 -modified sodium carbonate decahydrate phase-change suppressant, denoted as NWD, was prepared from Na 2 CO 3 ·10H 2 O and hydrophobic nano-SiO 2 to suppress MgH 2 dust explosions. NaHCO 3 was also tested as a conventional sodium-based suppressant for comparison. At an inerting ratio of 3.0, NWD reduced P max to 0.368 MPa and K st to 3.013 MPa m/s, corresponding to reductions of 70% and 94.3%, respectively, while the Pmax of the NaHCO 3 -treated system remained at 0.672 MPa. NWD suppresses MgH 2 dust explosions through synergistic heat absorption, water-vapor dilution, porous condensed-phase coating, oxygen/heat-transfer blocking, and sodium-related radical scavenging. This work provides a potential strategy for the safe storage and utilization of MgH 2 .