Fluorination-Initiated Reaction Pathways in Al/CuO/B/Viton Composites and Their Effect on Underwater Explosion Performance

This study designed an energetic composite system of Al/CuO/B/Viton to investigate the correlation between formulation parameters and underwater energy output. A series of formulations were constructed by adjusting the fuel-to-oxidizer equivalence ratio (Φ) from 1.5 to 3.0. The thermal decomposition behavior and reaction behavior were systematically characterized using TG-DSC, TG-FTIR, and XPS. The Al/B-based composite was configured as the central charge with an annular RDX shell, and its energy output characteristics were evaluated through underwater explosion tests. Based on multi-scale characterization and kinetic analysis, a thermochemical reaction pathway involving fluorination-initiated surface activation, thermite reaction, and boron oxidation is proposed for the boron-containing thermite. The B1 formulation (6 wt% B, 10 wt% Al) exhibited distinctive bimodal combustion with a total duration of approximately 100 ms and achieved a bubble energy of 1.80 MJ/kg. Among the tested equivalence ratios, Φ = 2.5 gave the highest bubble energy, with both A3 and B3 achieving comparable values of approximately 2.03 MJ/kg. To decouple the contribution of aluminum from density-related effects, LiF was used as an inert substitute for Al in control samples, which exhibited substantially lower bubble energy of approximately 1.26 MJ/kg, indicating that the energy output is closely related to the reactive Al/CuO/B system. These findings demonstrate that formulation design can systematically influence the partition of shock wave and bubble energy.