Preparation and performance study of core shell B @ PTFE/AP composite micro unit structure

The application of boron-based solid rocket fuels has been constrained by their high oxygen consumption and processing challenges related to surface oxide layers. This study developed a ternary core-shell structured B@PTFE/AP system with adjustable mass ratios through planetary ball milling, determining the optimal composition as B (11.6 %), PTFE (1.6 %), and AP (86.8 %). Initially, a binary B@PTFE system was fabricated, where SEM observations revealed that PTFE formed a dense and continuous coating on boron particles, achieving a 9.2 % enhancement in specific heat release and an 82.3 % oxidation weight gain rate. Upon introducing AP to construct the ternary system, TG-DSC analysis demonstrated that AP preferentially decomposed to release oxygen and energy, advancing the PTFE decomposition temperature by 50°C and generating HF and O₂. These products reacted with native B₂O₃ through a pre-ignition reaction to form gaseous BF₃, effectively removing the passivation layer and exposing active boron cores. Simultaneously, the continuous oxygen supply from AP decomposition established a self-enhanced cycle, maintaining oxidation weight gain rates consistently above 60 %. Combustion tests showed that the optimized ternary system achieved a reduced ignition delay of 0.78 s (ignition energy: 28.34 J) with an optimal AP:B@PTFE mass ratio of 6.6:1. This core-shell architecture overcomes traditional boron combustion limitations through component synergy, providing an advanced high-energy fuel solution for solid propellants.