Thermal Interaction Mechanisms of Ammonium Perchlorate and Ammonia Borane.

Ammonia borane (AB), with a theoretical hydrogen content of 19.6 wt%, is constrained by its low crystalline density (0.758 g/cm) and poor thermal stability (decomposing at 100 °C). In this study, AB/ammonium perchlorate (AP) composites were synthesized via freeze-drying at a 1:1 molar ratio. The integration of AP introduced intermolecular interactions that suppressed AB decomposition, increasing the onset temperature by 80 °C. Subsequent vacuum calcination at 100 °C for 2 h formed oxygen/fuel-integrated ammonium perchlorate borane (APB), which achieved decomposition temperatures exceeding 350 °C. The proposed mechanism involved AB decomposing into borazine and BN polymers at 100 °C, which then NHBH/ClO combined to form APB. At 350 °C, APB underwent the following redox reactions: 4NHBHClO → N↑ + 4HCl↑ + 2BO + NO↑ + O↑ + 7HO↑ + H↑, while residual AP decomposed. The composite exhibited improved density (1.66 g/cm) and generated H, N, O and HCl, demonstrating potential for hydrogen storage. Additionally, safety was enhanced by the suppression of AB's exothermic decomposition (100-200 °C). APB, with its high energy density and thermal stability, was identified as a promising high-energy additive for high-burning-rate propellants.