石墨烯取向影响石墨烯/硝酸盐复合材料传热性能的分子动力学模拟  

Effect of graphene orientation on heat transfer properties of graphene/nitrates composites by molecular dynamics simulation

作　　者：吴晨光 李蓓[1,2] WU Chenguang;LI Bei(Research Center for Materials Genome Engineering,School of Materials Science and Engineering,Wuhan University of Technology,Wuhan 430070,China;State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology,Wuhan 430070,China)

机构地区：[1]武汉理工大学材料科学与工程学院材料基因工程研究中心,武汉430070 [2]华中科技大学材料成形与模具技术国家重点实验室,武汉430070

出　　处：《复合材料学报》2022年第5期2495-2503,共9页Acta Materiae Compositae Sinica

基　　金：华中科技大学材料成形与模具技术国家重点实验室开放课题研究基金(P2021-009)。

摘　　要：采用非平衡分子动力学(NEMD)方法,以二元硝酸盐Solar salt(NaNO_(3)和KNO_(3)质量比为6∶4)为基体,石墨烯为填料,研究了石墨烯取向对石墨烯/硝酸盐复合材料界面热导的影响。研究发现,随着石墨烯平面与热流方向夹角的减小,体系热流密度升高、温差下降,界面热导从46.36 MW·m^(−2)·K^(−1)提升至80.03 MW·m^(−2)·K^(−1)。对复合材料中的原子振动态密度和微观结构进行表征,结果发现,随着石墨烯与热流夹角减小,界面处的热流从跨石墨烯平面运输转变为沿石墨烯平面的高效率运输,且加入石墨烯后硝酸盐会形成密度较大的致密层结构。同时,采用有效介质理论拟合了微观尺寸的石墨烯/硝酸盐复合材料热导率,结果表明,石墨烯平行于热流方向时复合材料热导率最高,且增加石墨烯体积分数及长度均有助于复合材料热导率的增强。The effects of the graphene orientation on interfacial thermal conductivity of graphene/nitrate composites with binary nitrate Solar salt(NaNO_(3)/KNO_(3) mass ratio of 6∶4)as substrate and graphene as filler was investigated by non-equilibrium molecular dynamics(NEMD)method.It is shown that the interfacial thermal conductance can be considerably enhanced from 46.36 MW·m^(−2)·K^(−1) to 80.03 MW·m^(−2)·K^(−1) as the angleθbetween the graphene surface and the heat flux direction(i.e.,z direction)decreases from 90°to 0°.As the angleθdecreases,the effective projection of the graphene plane in the direction of heat flow is enhanced,and more heat will be transported along the graphene plane.The results of the vibrational density of state(DOS)clearly signify that heat flow at the interface changes from transport across the graphene plane to efficient transport along the graphene plane with the decrease of angle between graphene and heat flow.Moreover,the nitrates form a similar dense layer around the graphene for all different orientation angles,which would also promote the enhancement of the thermal conductance.Finally,the thermal conductivity of the graphene/nitrates composites with different orientations at the microscale is predicted by the effective medium theory.It is found that the thermal conductivity of the composite decreases with the orientation angle,but increases with the volume fraction and the length of the graphene.

关 键 词：分子动力学 界面热导 石墨烯 振动态密度 有效介质理论 

分 类 号：TB33[一般工业技术—材料科学与工程]