Liquid Carbon-Boron Cluster Additives for Mixed Amine-50

Boron-containing compounds, known for their high calorific value, can significantly enhance the energy density of traditional liquid propellants. Through precise chemical modification of the C-H bonds in <i>ortho</i>-carborane, a novel liquid cluster material was synthesized: C,C'-Bis(2-ethylhexanoylmethyl)-<i>o</i>-carborane (<b>BEHMC</b>). This compound exhibits excellent stability, density, and energy properties. By combining <b>BEHMC</b> with mixed amine-50, a cluster liquid propellant was formulated, and its key performance metrics such as density, freezing point, mass calorific value, and volumetric calorific value were evaluated. The propellant achieved a density of 0.884 g·cm^-3, a freezing point below -55 °C, a mass calorific value of 41.13 kJ·g^-1, and a volumetric calorific value of 36.36 kJ·cm^-3. The theoretical specific impulse reached 346 s, and the theoretical density impulse was 2.99 × 10⁶ N·s·m^-3. Compared to the traditional mixed amine-50/red fuming nitric acid propellant, the cluster liquid propellant developed in this study maintains a similar calorific value while improving the theoretical specific impulse and density impulse by 2.3% and 3.8%, respectively.