Effect of stearic acid coating on the flame propagation and reaction mechanism of AlH3

Abstract

AlH3 is considered to be the most promising high-energy additive and stearic acid (SA) is a common passivation coating material to enhance stability. To explore the effect of coating of SA on AlH3, flame propagation and reaction mechanisms are compared through ignition experiments and ReaxFF molecular dynamics, respectively. The flame propagation of AlH3/SA slowed down for ∼20 ms and the flame duration is longer for ∼50 ms, indicating that the combustion intensity is reduced. The combustion reaction of AlH3 is initiated through the release of •H by H-Al breaking and further oxidizing to form H2O and Al-O clusters. The presence of SA results in more O and C atoms contained in the system and more reaction paths. The addition of C atoms and O atoms makes the maximum cluster molecular weight of AlH3/SA increase by 0.1 × 10^4 than AlH3. The results of flame propagation and reaction mechanisms verify that the stability of AlH3 is improved by the coating of SA.