Reactive molecular dynamics simulation of thermal decomposition for nano-aluminized explosives

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Engineering

Background:

• Aluminized explosives are crucial for construction and military applications.
• The thermal decomposition mechanisms of aluminized explosives remain poorly understood.
• Understanding these mechanisms is vital for optimizing performance and safety.

Purpose of the Study:

• To investigate the thermal decomposition mechanisms of TNT, RDX, HMX, and CL-20 when combined with aluminum nanoparticles.
• To elucidate the role of aluminum nanoparticles in altering explosive decomposition pathways and kinetics.
• To provide a molecular-level understanding of the interactions between explosives and aluminum during thermal events.

Main Methods:

• Reactive dynamics simulations were employed using a newly parameterized reactive force field with low gradient correction (ReaxFF-lg).
• Partially passivated aluminum nanoparticles were modeled and mixed with TNT, RDX, HMX, and CL-20 crystals.
• Simulated systems were heated to high temperatures to induce and observe complete explosive decomposition.

Main Results:

• Thermal decomposition occurred in three distinct stages: adsorption (0-20 ps), diffusion (20-80 ps), and formation (80-210 ps).
• Aluminum nanoparticles reduced decomposition reaction barriers for RDX, HMX, and CL-20, and significantly for TNT.
• Energy release increased, H2O production rose (25.27-27.81%), and CO2 generation decreased (47.73-68.01%) compared to crystalline explosives.

Conclusions:

• Aluminum nanoparticles act as catalysts, lowering decomposition barriers and modifying product distribution in explosives.
• The observed three-stage decomposition process is consistent across different explosives studied.
• Simulation results align with experimental observations, particularly regarding onset temperatures for product formation.