Exploding wire preparation of core–shell aluminum–silicon nanoparticles and characterization as energetic material

Novel aluminum–silicon (Al–Si) nanoparticles (11 ~ 12 wt.% silicon) with core–shell structure were designed and prepared by electric wire explosion in argon atmosphere. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and composition of Al–Si powders. Oxygen bomb calorimeter was used to obtain the combustion heat released, whereas thermo-gravimetric analysis and differential scanning calorimetry (TG-DSC) were used to study the thermal oxidation process. Results showed that the particle size of Al–Si powders with d₅₀ of 311.8 nm was mainly in the nanometer range, although some large particles of several micrometers were observed. The nanoparticles had a typical “core–shell” structure. The shell consisted of silicon chips and aluminum oxides, whereas core is mainly composed of silicon frameworks filled with aluminum. TG-DSC results showed that the thermal oxidation reaction of Al–Si nanoparticles in the air proceeded in three stages. The first stage involves the slow oxidation reaction, whereas in the second step there is a violent oxidation reaction of Al, which started at about 535.5 ℃. The third step involves the mild oxidation of Al and Si. The weight gain was 72%. The oxygen bomb calorimeter tests showed that the heat release of Al–Si powders was higher than that of pure nano-Al powders. Therefore, the Al–Si nanoparticles prepared in the present work can be considered as a promising candidate in composite energetic materials such as explosives and propellants.