Investigation into Thermal Decomposition Mechanisms of Al-Coated CL-20-Based Cocrystal Explosives via Reactive Molecular Dynamics Simulations

This study used reactive molecular dynamics (RMD) simulations to systematically investigate the thermal decomposition characteristics of Al-coated CL-20-based cocrystal explosive (CL-20/BTF@Al and CL-20/TNT@Al) nanoparticles at 2500 K, revealing how metallic Al exerts regulatory effects on the thermal decomposition mechanisms of energetic materials compared with the pure CL-20-based cocrystal system. The results indicate that the Al-coated structure could create a large number of local high-temperature hotspots in the system, providing active sites to initiate reactions, while slowing down heat loss and increasing the system temperature. The evolution of thermal decomposition products indicates significant differences between the Al-coated systems and the pure cocrystal systems, confirming that Al effectively regulates the thermal decomposition pathway. Atomic diffusion analysis shows that the exothermic reaction of Al promotes the decomposition of intermediates, increases the content of small molecules containing free H and N, and thereby enhances the diffusion coefficients of H and N atoms. In addition, Al combines with O to form stable clusters, which adsorb bound carbon fragments at their interfaces, significantly inhibiting the migration and diffusion of C and O atoms, thereby reducing their diffusion coefficients. This work clarifies the microscopic thermal reaction mechanism of metal/energetic composites from an atomic-scale perspective, and lays an essential theoretical foundation for component formulation and performance optimization of high-efficiency energetic composites.