Preparation and Performance of Core–Shell Structured B@NiF2/AP Composite Micro-Units

Boron (B) powder is a promising high-energy fuel but suffers from inefficient combustion due to its native boron oxide (B2O3) passivation layer. Surface coating is a crucial strategy to overcome this limitation. In this study, core–shell structured B@NiF2/ammonium perchlorate (AP) composite micro-units with varying mass ratios were prepared using planetary ball milling to optimize energy release and combustion performance. The optimal formulation for the ternary composite was determined to be 0.5% NiF2, 13.3% B, and 86.2% AP. Morphological characterization revealed that NiF2 was uniformly coated on the B particles, forming a dense shell. Thermal analysis indicated that the NiF2 interfacial layer, through its high-temperature decomposition (NiF2 → Ni + 2F·), released highly reactive fluorine radicals (F·) that etched the B2O3 layer, generating volatile boron oxyfluoride and creating void structures. This led to a maximum heat release of 8912 J/g and a reaction mass gain of 74.58%, indicating more complete combustion. The material also exhibited a minimal ignition delay of 0.618 s and the lowest ignition energy (22.17 J). Overall, the B@NiF2/AP composite provides a novel solution for applying boron fuel in solid propellants and pyrotechnic technologies.