纳米铝颗粒在不同炸药环境中氧化燃烧的分子动力学模拟

Oxidation and Combustion of Aluminum Nanoparticles in Different Explosive Environments by Molecular Dynamics Simulation

为探索炸药环境对纳米铝颗粒(ANP)氧化燃烧的影响,采用分子动力学模拟方法,研究了程序升温加热、恒温加热及绝热加热下ANP在硝化甘油(NG)、黑索今(RDX)和三氨基三硝基苯(TATB)环境中的氧化燃烧机理。结果表明,NG、RDX和TATB对ANP的氧化性依次减弱,对燃烧的微观机制产生了不同的影响。在氧化形貌上,随着炸药环境氧化性的减弱,ANP在急速升温下发生崩裂的程度减弱,氧化速度变慢,最终形成的Al团簇中Al原子的主要配位数从NG环境中的7配位下降为TATB环境中的6配位。并且在TATB环境中,ANP上解离的Al原子在环境中形成了原子数约为100的大团簇结构,这也抑制了ANP的氧化进程。在团簇数量上,程序升温加热下不同炸药环境间的差异较小。而在恒温加热和绝热加热下,随着炸药环境氧化性的减弱,ANP崩裂后形成的Al团簇数量减少,并且由于小Al团簇在氧化性弱的环境中不易团聚,此后Al团簇数量会在短时间内持续增加。在化学反应特性上,NG环境中的ANP主要与炸药分解的含氧产物反应,导致形成的Al团簇氧化更加完全。而在RDX和TATB环境中,ANP还能与N2、CN等不含氧产物发生大量反应,导致形成的Al团簇中包含较多的C、H、N原子,Al团簇的氧化并不完全。

In order to explore the effects of explosive environments on the oxidation and combustion of aluminum nanoparticles(ANP),the mechanisms of high temperature combustion of ANP in nitroglycerin(NG),1,3,5⁃trinitro⁃1,3,5⁃triazine(RDX)and 1,3,5⁃triamino⁃2,4,6⁃trinitrobenzene(TATB)environments under different heating methods were studied by molecular dynamics simulation.The results show that the oxidation capacity of NG,RDX and TATB to ANP reduces in order,and the different explo⁃sive environments have different effects on the microscopic mechanism of combustion.As the oxidizability of explosive environ⁃ment becomes weaker,the degree of ANP crack weakens at rapid heating,and with the oxidation becomes slower,the main co⁃ordination number of Al atom in final formed Al cluster decreases from 7 in NG environment to 6 in TATB environment.Besides,the dissociated Al atoms from ANP form some large Al clusters with about 100 atoms in the TATB environment,which also inhib⁃its the oxidation of ANP.There is little difference on the number of Al clusters between different explosive environments at pro⁃grammed heating.However,the number of Al clusters formed after ANP cracks is less as the oxidizability of the explosive environ⁃ments decreases at constant heating and adiabatic heating.The number of Al clusters continues to increase in a short time thereaf⁃ter due to the reason that the small Al clusters are less likely to agglomerate in a weakly oxidizing environment.ANP in NG envi⁃ronment mainly reacts with the oxygen⁃containing products decomposed from explosives,and the formed Al clusters are oxidized more completely.Nevertheless,ANP could react with N2,CN and other oxygen⁃free products in RDX and TATB environments,which leads to the formation of Al clusters containing C,H and N atoms,and thus the oxidation of Al clusters is not complete.