Reactive molecular dynamics simulation of thermal decomposition for nano-AlH₃/TNT and nano-AlH₃/CL-20 composites

Using reactive molecular dynamics method with the reactive force field framework, the thermal decomposition of nano-AlH₃/TNT and nano-AlH₃/CL-20 composites was investigated to develop new high explosives. The binding energies and relaxed densities of the composites show that the compatibility of TNT/AlH₃ is better than CL-20/AlH₃, which is confirmed by the DFT calculations. The pyrolysis simulations showed that the potential barrier of TNT/AlH₃ (1.14 kJ g⁻¹) and CL-20/AlH₃ (0.72 kJ g⁻¹) are smaller than pure TNT (1.99 kJ g⁻¹) and pure CL-20 (1.01 kJ g⁻¹), respectively. This indicates the catalytic effect of AlH₃ nanoparticle on the decomposition of TNT and CL-20. The catalytic effect was confirmed by the DFT calculations of the R–NO₂ rupture of TNT and CL-20 molecules on AlH₃ surfaces. The slower heating rate (r_h) of 16 K ps⁻¹ led to similar evolution results as r_h = 32 K ps⁻¹, which implies that the dependence of the simulation results on the heating rate is small. Moreover, TNT/AlH₃ and CL-20/AlH₃ release 1.07 and 1.97 kJ g⁻¹ more energies and generate 33.8% and 14.0% more total gas products than pure TNT and CL-20, respectively. Therefore, AlH₃ nanoparticles can improve the detonation performance and specific impulse for TNT and CL-20. These are in accord with the effect of AlH₃ on nitromethane and ammonium perchlorate/hydroxyl-terminated polybutadiene propellants in the experiments. As a result, the nano-AlH₃/TNT and nano-AlH₃/CL-20 composites can be promising candidates of new high explosives.