Fabrication and regulation of combustion properties for Al-Li composite fuel utilizing copper perfluorooctanoate in solid propellant

Alloy based composite fuel has been widely studied for its higher combustion effect and energy release, compared with traditional metal fuels. The doping of organometallic salt was the key to facilitating the mass and heat transfer process in propellant combustion. In this study, the Al-Li particles were stabilized through tris(hydroxymethyl)aminomethane hydrochloride (TH) firstly, and the copper perfluorooctanoate Cu(PFO)₂ was obtained through a double displacement reaction and characterized by X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), Ultraviolet–visible spectroscopy (UV–vis), scanning electron microscope (SEM) and thermogravimetric analysis and differential scanning calorimeter (TG-DSC) tests. Owing to the characteristics of easy film formation, the Cu(PFO)₂ could be attached to the passivated Al-Li@TH surface through the solvent evaporation method with good hydrophobicity. The thermal oxidation and combustion characteristics were evaluated by TG-DSC and ignition test for the Al-Li@TH@Cu(PFO)₂ and propellants. The Al-Li@TH@5Cu(PFO)₂ propellant had a faster burning rate of 1.21 mm s⁻¹, a shorter ignition delay time of 0.67 s, a higher combustion temperature of 1411.26 °C and smaller combustion residue distribution with an obvious micro-explosion effect and more stable combustion. The existence of AlF₃ also proved that the release of corrosive gases produced by Cu(PFO)₂ decomposition, which could effectively promote the rupture of Al-Li alloy shell. Besides, the activation energy of Al-Li@TH@5Cu(PFO)₂ and AP could be reduced to 139.37 kJ mol⁻¹ with a better catalytic effect. The combustion mechanism had also been analyzed through the combustion phenomena and residue composition. The exploration of propellant combustion could offer a promising avenue for applying Al-Li alloys in various propulsion systems.