Study on preparation, ignition and combustion performance of high activity boron-based composite micro-units

To improve the application value of fuel boron (B), the B/iron fluoride (FeF3) binary composite micro-units with FeF3 as the active agent are successfully prepared by a high-speed ball milling method. In addition, potassium perchlorate (KP) is also employed as the oxidizing enhancer, and the B/FeF3/KP ternary composite micro-units is prepared by the solvent-nonsolvent method. The results of morphology and structure show that FeF3 particles are embedded on the surface of B, forming a close contact structure. The thermal analysis shows that the oxidation reaction temperature of B gets a substantial reduction, which is reduced with a maximum of 24 % (191 degrees C) compared to the physical mixed sample. It is worth noting that the pre-ignition reaction (PIR) of the B/FeF3 composite micro-unit occurred at 476 degrees C, which has a double activation effect. Because FeF3 reacts with boron oxide (B2O3) on the surface of B to generate gaseous boron fluoride (BF3) and iron oxide (Fe2O3). The formation of BF3 makes the B2O3 film removed, which leads to the oxidation exothermic reaction of B faster. Moreover, as an excellent burning rate catalyst, the formation of Fe2O3 in PIR also increases the energy transfer rate and the reaction activity of composite micro-units. The ignition and combustion test results indicate that all B/FeF3/KP composite micro-unit samples can be successfully ignited and self-sustain combustion. The combustion intensity, flame volume, and temperature of the ternary composite micro-unit with 6 % FeF3 content reach the maximum, and it has the best ignition and combustion performance.