Accelerating the Combustion of Aluminum Diboride (AlB₂) Fuel with Functionalized Carbon Nanomaterials

Aluminum diboride (AlB₂) has been proposed as a viable substitute for elemental boron as the fuel for boron-containing solid propellants, owing to its favorable compatibility with propellant formulations, high gravimetric heat of combustion, and the anticipated synergistic effects from boron and aluminum. Nevertheless, its practical implementation is impeded by intrinsically low energy-release rates and pronounced agglomeration. In this study, two-dimensional graphene fluoride (GF), three-dimensional polytetrafluoroethylene (PTFE), and two-dimensional graphene oxide (GO) were strategically incorporated to construct composite fuel systems capable of fully exploiting the energetic potential of AlB₂. Laser-ignition experiments demonstrated that GF, GO, and PTFE all generate abundant gaseous products while markedly intensifying the combustion of AlB₂, while GF exhibits better enhancing effects. Thermal analyses reveal that fluorinated additives markedly enhance the thermal oxidation characteristics of AlB₂, effecting a pronounced reduction in its initial decomposition temperature. The difference in the combustion mechanism of AlB₂ with GF and GO lies in the fluorine, although they both open alternative reaction pathways, GF exhibits more notable capacity to suppress agglomeration of condensed combustion products. The formulation developed and mechanisms revealed by this work could potentially advance the applications of boron-based fuels in ramjets and scramjets.