摘要
为研究六硝基六氮杂异戊兹烷(CL-20)的高温热膨胀及相变规律,采用分子动力学方法和价角势能截距修正的ReaxFF-lg反应力场,考察了ε-、β-和γ-CL-20的相变温度和热膨胀系数。为验证力场适用性,计算了常温下三种晶型CL-20的密度、晶胞参数、晶格能和升华焓。采用三阶Birch–Murnaghan状态方程拟合了0~280 GPa压力范围内ε-CL-20的p-V曲线,得到体积模量及随拟合压力升高的变化规律。高温相变分析表明,ε-和γ⁃CL-20在398~423 K产生相变,其中ε→γ相变在常压下发生,而γ→ε相变需加压0.5 GPa以上;β-CL-20在448 K下转变为ε晶型。热膨胀系数分析表明,ε-CL-20高温热膨胀过程无明显各向异性,而β-和γ-CL-20分别在c方向和b方向表现出各向异性。研究结果表明,修正的ReaxFF-lg反应力场适用于ε-、β-和γ-CL-20的高温高压相变研究,对于β-和γ-CL-20的热膨胀研究精度有待进一步提高。
In order to analyze high temperature phase transformation of hexanitrohexaazaisowurtzitane(CL-20),phase transformation temperatures and coefficients of thermal expansion ofε-,β-,andγ-CL-20 were studied via ReaxFF-lg reactive force field molecular dynamics,with modified valence potential intercept.To validate the applicability of selected force field,the density,cell constant,lattice energy,and sublimation enthalpy for three types of CL-20 at room temperature were calculated.The third order Birch-Murnaghan equation of state was used to fit the p⁃V curve ofε-CL-20,with pressure ranging from 0 to 280 GPa.And the variation of bulk modulus(B0)and its partial derivative to pressure(B′0)with the increase of pressure is analyzed.High tem-perature phase transformation analysis shows thatε-andγ-CL-20 change phases at 398-423 K,of which theε→γphase transition occurs at atmospheric pressure,while theγ→εphase transition needs 0.5 GPa or higher pressure;β-CL-20 transforms toεcrystal form at 448 K.The thermal expansion coefficient analysis shows that there is no obvious anisotropy in the high temperature thermal expansion process ofε-CL-20,whileβ-andγ-CL-20 show anisotropy in c direction and b direction,respectively.Results show that the modified ReaxFF-lg reactive force field is suitable for the study of phase transition ofε⁃,β⁃,andγ-CL-20 at high temperature and high pressure,while the accuracy of thermal expansion ofβ-andγ-CL-20 needs to be further improved.
作者
李昌霖
甘强
冯长根
胡靖伟
朱双飞
程年寿
LI Chang-lin;GAN Qiang;FENG Chang-gen;HU Jing-wei;ZHU Shuang-fei;CHENG Nian-shou(State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,Beijing 100081)
出处
《含能材料》
EI
CAS
CSCD
北大核心
2021年第4期325-331,共7页
Chinese Journal of Energetic Materials
基金
爆炸科学与技术国家重点实验室(北京理工大学)自主课题资助(QNKT20-04)。
关键词
CL-20
ReaxFF-lg反应性力场
价角势能修正
高温高压相变
热膨胀
CL-20
ReaxFF-lg reactive force field
modified valence angle potential energy
high temperature and pressure phase transfromation
thermal expansion
