Energy release properties of amorphous boron and boron-based propellant primary combustion products

The microstructure of amorphous boron and the primary combustion products of boron-based fuel-rich propellant (hereafter referred to as primary combustion products) was analyzed by scanning electron microscope. Composition analysis of the primary combustion products was carried out by X-ray diffraction and X-ray photoelectron spectroscopy. The energy release properties of amorphous boron and the primary combustion products were comparatively studied by laser ignition experimental system and thermogravimetry-differential scanning calorimetry. The primary combustion products contain B, C, Mg, Al, B4C, B13C2, BN, B2O3, NH4Cl, H-2, and so on. The energy release properties of primary combustion products are different from amorphous boron, significantly. The full-time spectral intensity of primary combustion products at a wavelength of 580 nm is similar to 2% lower than that of amorphous boron. The maximbm spectral intensity of the former at full wave is similar to 5% higher than that of the latter. The ignition delay time of primary combustion products is similar to 150 ms shorter than that of amorphous boron, and the self-sustaining combustion time of the former is similar to 200 ms longer than that of the latter. The thermal oxidation process of amorphous boron involves water evaporation (weight loss) and boron oxidation (weight gain). The thermal oxidation process of primary combustion products involves two additional steps: NH4Cl decomposition (weight loss) and carbon oxidation (weight loss). CL-20 shows better combustion-supporting effect than KClO4 in both the laser ignition experiments and the thermal oxidation experiments. (C) 2015 IAA. Published by Elsevier Ltd. All rights reserved.