关键词: 富碳炸药, 团簇分子, ReaxFF/lg, 类石墨, 体积膨胀

The clusters can be seen in carbon-rich explosives during detonation. However, we can't directly observe the formation of clusters by experimental methods. The thermal decomposition of TNT at various temperatures are studied using ReaxFF/lg molecular dynamics simulations. The ReaxFF/lg force field provides detailed information on the formation of cluster from atomic level, the stability of the clusters and the graphite-like structures. The results show that clusters formed slowly at the initial reaction with increasing the relative molecular mass of a TNT approximately one time. As the reaction proceeding, the mass of clusters increases rapidly, and the molecular weight of max cluster can reach 8000~10000 (amu), accounting over about 18% of the system mass. Analysis of the structure of the clusters reveal that some benzene rings in the clusters were broken, and five-membered rings and the six-membered rings which contain N and O atoms were formed, and the more complex seven-membered rings structure were formed under the 3500 K condition. Through the method of linear expansion and direct cooling, the stability of the clusters was studied:the clusters decomposed rapidly by the method of linear expansion, while the clusters aggregated into larger clusters by the method of direct cooling. Through the analysis of graphite-like structures, we obtain that it is an essential step to first expand and the cool down second by analysis the production process of graphite-like structures. The mass ratio of C atoms in the clusters has been increasing during the reaction process by comparing the ratio of the mass of each atom in the clusters and TNT molecules, while the mass ratio of N atoms and H atoms in the clusters decrease and the mass ratio of O atoms show more complicated during the whole reaction. This study can provide a good basis for the preparation of new nanomaterials for detonation of TNT.

Key words: carbon-rich explosive, cluster, Reaxff/lg, graphite-like, volume expansion