Stabilization of AlH3 Crystals by the Coating of Hydrophobic PFPE and Resulted Reactivity with Ammonium Perchlorate

Aluminum hydride (AlH₃) is a promising fuel component of solid propellant, but its stabilization is still challenging. Herein, surface functionalization of hydrophobic perfluoropolyether (PFPE) followed by ammonium perchlorate (AP) coating has been implemented. In particular, AlH₃@PFPE@xAP (x = 10, 30, 50, or 64.21%) composites (AHFPs) were prepared by a spray-drying technique. The PFPE-functionalized AlH₃ with a hydrophobic surface shows an increased water contact angle (WCA) from 51.87° to 113.54°. Compared with pure AlH₃, the initial decomposition temperatures of AHFPs were increased by 17 °C, and the decomposition properties of AP in the AHFPs were also enhanced with significantly decreased peak temperature and fairly increased energy output. Moreover, the decomposition induction time of AHFPs-30% was improved by almost 1.82 times that of raw AlH₃, which indicates that the coatings of PFPE and AP could improve the stability of AlH₃. The maximum flame radiation intensity of AHFPs-30% was 21.6 × 10³, which is almost 7.71 times that of pure AlH₃ (2.8 × 10³).