共晶炸药晶体稳定性和爆轰能量提升策略的理论研究

为探究影响共晶炸药晶体稳定性和爆轰能量的关键因素,基于第一性原理方法对六硝基六氮杂异伍兹烷/奥克托今(CL-20/HMX)、六硝基六氮杂异伍兹烷/三硝基甲苯(CL-20/TNT)、苯并三氧化呋咱/1,3,5-三硝基苯(BTF/TNB)、3-硝基-1,2,4-三唑-5-酮/5,6,7,8-四氢四唑并三嗪(NTO/TZTN)等16种共晶炸药的晶体结构、分子间相互作用、物理化学性质参数、晶体稳定性及爆轰能量进行了研究。结果表明,分子间氢键强度小于21 kJ·mol~(-1)时,共晶晶体稳定性主要由氢键数量决定;氢键强度大于21 kJ·mol~(-1)时,共晶晶体稳定性主要由氢键强度决定。相对于单组分炸药,共晶炸药大多具有较好的氧平衡和氮含量,但晶体密度普遍较小,导致爆轰能量相对于单组分炸药并无明显优势。以CL-20共晶炸药为例,共晶设计需提升分子间氢键的强度,而非仅增大氢原子计量比、增加氢键数量以提升晶体稳定性。该策略能兼顾较好的氧平衡、氮含量和晶体密度,从而实现共晶炸药晶体稳定性和爆轰能量的实质性提升。

Theoretical Study on Improvement Strategy of Crystal Stability and Detonation Energy of Cocrystal Explosive

The calculations of the crystal structures, in-crystal intermolecular interactions, physicochemical properties, crystal stability and detonation performance for 16 reported cocrystal explosives were carried out to explore their effect on crystal stability and detonation performance of cocrystal explosives. We show that the crystal stability of the cocrystal explosives is mainly determined by the hydrogen bonding (HB) amount when the HB strength is less than 21 kJ·mol^-1. When the HB strength is more than 21 kJ·mol^-1, the crystal stability of the cocrystal explosives is mainly determined by the HB strength. Compared to traditional single-component explosives, the reported 16 cocrystals exhibit better nitrogen content and oxygen balance, but their material densities and detonation performance are less competitive. Through the analysis of CL-20 cocrystal explosives, it is theoretically suggested that enhancing HB strength, instead of introducing more hydrogen atoms to increase HB amount, could be useful to improve crystal stability of cocrystal explosives. This strategy can simultaneously meet the requirement of oxygen balance and nitrogen content in resulting satisfactory detonation performance of cocrystal explosives.