A novel nano-thermite system with BiOF as fluorine-containing oxidant for enhanced energy release performance

Abstract

The reduced diffusion distance of nano-thermite results in an exceptionally high energy release rate and intense exothermic reactions upon ignition, which has drawn significant interest from researchers in the field of energetic materials. With the deepening of research, metal fluorides are gradually favored by researchers because of their unique reaction characteristics. This paper presents the synthesis of a new fluorine-containing oxidant, BiOF, and its use in the preparation of a novel nano-thermite with n-Al. BiOF crystals exhibit a unique microscopic morphology and are interlaced into “nanoflower” microspheres, which allows for good interfacial contact between the oxidant and fuel during the recombination process. The resulting n-Al/BiOF system displays excellent ignition and combustion performance, with a combustion temperature higher than the boiling point of its main combustion products, AlF3 and Bi. Compared with n-Al/CuO and n-Al/MoO3 systems, n-Al/BiOF exhibits a higher flame propagation rate under confinement. In addition, the ignition threshold of the n-Al/BiOF system is also smaller than that of the n-Al/CuO and n-Al/MoO3 systems. Furthermore, the paper examines the reaction mechanism of the n-Al/BiOF system through thermal reaction path analysis and combustion and thermal analysis product characterization. The paper discovers a “pre-ignition” reaction mechanism before the ignition temperature, where the strongly electronegative fluorine in BiOF corrodes the Al2O3 shell, promoting the release of aluminum energy. The synergistic and effective interaction between oxygen, fluorine, and fuel aluminum in the n-Al/BiOF system results in efficient energy release performance, making BiOF a promising candidate for n-Al based reactive materials in propellants, explosives, and pyrotechnic products.