物理化学学报 >> 2013, Vol. 29 >> Issue (06): 11451145-1153.doi: 10.3866/PKU.WHXB201303221

热力学,动力学和结构化学 上一篇    下一篇

水分子对α相CL-20热分解机理影响的分子动力学研究

张力, 陈朗, 王晨, 伍俊英   

  1. 北京理工大学爆炸科学与技术国家重点实验室, 北京 100081
  • 收稿日期:2013-01-31 修回日期:2013-03-22 发布日期:2013-05-17
  • 通讯作者: 伍俊英 E-mail:1115636784@qq.com

Molecular Dynamics Study of the Effect of H2O on the Thermal Decomposition of α Phase CL-20

ZHANG Li, CHEN Lang, WANG Chen, WU Jun-Ying   

  1. State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, P. R. China
  • Received:2013-01-31 Revised:2013-03-22 Published:2013-05-17

摘要:

研究六硝基六氮杂异伍兹烷(CL-20)晶体不同晶型在不同温度下的反应机理, 对于深入认识含能材料在极端条件下的冲击起爆、冲击点火和爆轰过程等具有重要意义. 基于反应力场, 研究水分子在纯α相CL-20及其水合物的晶体结构中数量随时间的变换, 分析水分子对两种体系的初始分解和第二阶段的分解路径的影响. 计算结果表明: CL-20 分子的初始分解路径与水分子无关, 第二阶段的分解反应与水分子有关. 在低温(T<1500 K)下, 水分子对两种体系没有影响, 二者的初始分解路径均为N-NO2键生成NO2自由基; 在1500 K≤T≤2500 K时, 水分子作为反应物或与NO2、、OH自由基等组成催化体系, 生成O2、H2O2等产物, 加速水合物体系在高温下的第二阶段反应, 使得高温下水合物体系的化学反应速率和反应生成的NO2自由基的数量比纯CL-20体系的化学反应速率和反应生成的NO2自由基的数量大; 在T>2500 K时, 水分子的催化反应抑制CL-20初始分解反应, 使得在3000 K时纯CL-20体系的反应速率大于水合物体系中CL-20的反应速率.

关键词: CL-20, 水分子, 热分解, 反应路径, 催化体系, ReaxFF, 分子动力学

Abstract:

The response of the mechanisms of the α polymorph of CL-20 (α-CL-20) to high temperature is important for understanding the phenomenon of shock initiation, shock ignition, and detonation. The thermal decomposition of α-CL-20 hydrate and pure α-CL-20 were studied by ReaxFF reactive molecular dynamics simulations to obtain the time evolution of water molecules and the effect of H2O on the mechanisms of CL-20 at high temperatures. It was determined that the initial decomposition mechanisms of CL-20 are not dependent on the presence of water, but the secondary reaction pathways are. At low temperatures (T<1500 K), there is no relationship between the H2O, hydrate CL-20, and pure CL-20 systems, as the mechanism is only the dissociation of the N―NO2 bond to form the NO2 radical. At high temperatures (1500 K≤T≤2500 K), water molecules act as a reactant or form catalytic systems with NO2 radical to form OH radical, leading to the formation of O2, H2O2, and other products. Water molecules accelerate the secondary stage reaction of hydrate systems, leading to increased secondary reaction rates and number of NO2 radicals in the CL-20 hydrate compared with the pure CL-20 system. At very high temperatures (T>2500 K), the dissociation of water molecules competes with the initial thermal decomposition pathway of CL-20, leading to a larger rate constant for the pure CL-20 than for the hydrate CL-20.

Key words: CL-20, Water molecule, Thermal decomposition, Reaction pathway, Catalytic system, ReaxFF, Molecular dynamics

MSC2000: 

  • O642