High-efficiency synthesis of B@Mg@KNO3 by solvent extraction enhances the ignition and energy release performance of B

Boron (B) is widely acknowledged as the preferred fuel for rocket ramjets. Nevertheless, the presence of boron oxide (B ₂O ₃) on the surface of boron impedes the interaction between the oxidized component and the internal active component B, leading to challenges in ignition and constraints on reactivity and combustion efficiency. To mitigate these issues, high-energy materials featuring a B@Mg@KNO ₃ coating structure were efficiently and expeditiously prepared using a solvent extraction method. The B@Mg@KNO ₃ material distributes magnesium inside and outside the B shell, while KNO ₃ serves as the load layer. The addition of the load layer facilitates closer contact between Mg and the oxidizer, reducing the diffusion distance between oxygen and fuel. As a result, the ignition energy of B is reduced, and the energy release characteristic of B is improved through multi-effect coordination. In comparison with the B/KNO ₃ sample, the heat release of B@Mg@KNO ₃ increased by 113.1 %, the ignition temperature decreased by 50 °C, and the ignition energy decreased by 62.5 % as indicated by the ignition test. The flame temperature increased by 51.8 %, the combustion efficiency of B@Mg@KNO ₃ increased by 23.92 %, and the apparent activation energy decreased by 109.6 kJ/mol. Consequently, B@Mg@KNO ₃ is anticipated to expedite the application and advancement of boron-based rocket ramjet engines.