A comparative investigation of the explosion mechanism of metal hydride AlH3 dust and Al/H2 mixture

Abstract

Aluminum hydride (AlH3) is an excellent hydrogen storage material, whereas hydrogen is easily released because of the low-temperature dehydrogenation characteristic. Therefore, the explosion mechanism of AlH3 dust is explored by comparison with the Al/H2 mixture. The findings indicate that since the residual aluminum after hydrogen evolution combusts more completely, AlH3 has a higher explosion pressure value than Al/H2 mixture. However, the explosion pressure rise rate and average flame propagation velocity of AlH3 dust are lower than those of Al/H2 mixture. It is attributed to the initial free hydrogen state and initial higher hydrogen concentration of Al/H2 mixture. The key radicals that generate main explosion residues Al2O3 are AlO and O. AlH3(+M) ≤> AlH + H2(+M) has the greatest sensitivity on the formation of O and AlO. Hydrogen combustion expedites the phase transition process of aluminum dust, while their competition for oxygen is not conducive to the formation of Al2O3.