目的 全面系统地理解石墨烯散热膜结构与性能的关系。方法 选择了4种石墨烯散热膜试样,通过SEM、AFM、Raman、XRD、XPS等,对石墨烯散热膜的微观形貌、结构成分进行了系统性的表征;结合激光导热仪、万能材料试验机、薄膜方阻测试仪以及差示扫描量热仪,测试了石墨烯散热膜的导热性能、力学性能、电学性能及热稳定性,分析了性能与结构之间的内在关联。结果 研究发现,较少的孔隙、良好的致密性有利于石墨烯散热膜形成良好的导热和导电通路,并且能够抵抗形变,保持良好的力学性能;而膜层表面的褶皱和层间空洞会降低热传导性能。其次,充分论证了石墨烯散热膜制备过程中,石墨烯基面的碳原子会发生重排,使其存在石墨化现象,形成石墨结构;并且,较少的结构缺陷和含氧量有利于声子传播,增强散热膜的导热性和导电性。此外,证明了碳氧比（C/O）增大,有利于提升石墨烯散热膜的导热性能。最后,研究表明石墨烯散热膜随着厚度增加,热导率降低;密度越高,导热系数相对较高,拉伸强度越大。结论 石墨烯散热膜的微观形貌与结构成分的结构特性间相互作用,协同影响,共同塑造了其在导热、力学、电学等方面的宏观性能。

The microscopic morphology and structural composition of graphene heat dissipation films are closely related to its macroscopic properties such as mechanical properties, thermal conductivity, and electrical conductivity. For guiding the structural design optimization and performing regulation of graphene heat dissipation films, the intrinsic correlation between multi-dimensional structures and properties was explored through comparing the structure-performance relationships of four different types of graphene heat dissipation films. A combination of advanced characterization techniques and performance testing instruments was adopted to systematically investigate the structure and performance of the samples.
For the characterization of microscopic morphology and structural composition, scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed. Meanwhile, a laser thermal conductivity meter, universal material testing machine, film square resistance tester, and differential scanning calorimeter were used to test the thermal conductivity, mechanical properties, electrical properties, and thermal stability of the graphene heat dissipation films, respectively. On this basis, the intrinsic correlation between the performance and structural characteristics of the films was analyzed in depth.
The characterization results of microscopic morphology via SEM and AFM show that pore content and compactness are key factors affecting the comprehensive performance of graphene heat dissipation films. Specifically, fewer internal pores and good overall compactness are conducive to the formation of continuous and unobstructed thermal and electrical conduction pathways in the films. This not only reduces the transmission resistance of heat and electrons but also enhances the structural integrity of the films, enabling them to resist external deformation and maintain excellent mechanical properties under service conditions. In contrast, obvious wrinkles on the film surface and voids between graphene layers will break the continuity of conduction pathways, cause scattering of phonons and electrons, and thus significantly reduce the thermal conductivity of the films, even affecting their mechanical stability.
The analysis of structural composition by Raman, XRD, and XPS demonstrates that the graphitization and chemical composition of graphene have a significant impact on the conduction performance of the films. During the preparation process of graphene heat dissipation films, carbon atoms on the graphene basal plane undergo ordered rearrangement under the action of process conditions such as temperature and pressure, triggering a distinct graphitization phenomenon and forming a regular graphite-like crystal structure. Moreover, fewer structural defects and lower oxygen content can minimize phonon scattering during transmission and reduce the hindrance of oxygen-containing functional groups to conduction. Additionally, it is confirmed that an increase in the carbon-oxygen ratio (C/O) contributes to improving the thermal conductivity of graphene heat dissipation films, as it reduces oxygen-containing functional groups and promotes graphitization.
Finally, in this research, the effect laws of film thickness and density on their performance are revealed. It is found that the thermal conductivity of graphene heat dissipation films shows a negative correlation with the thickness: as the thickness increases, the number of internal defects and interlayer interfaces increases, enhancing phonon scattering and reducing thermal conduction efficiency. In contrast, density has a positive correlation with thermal conductivity and tensile strength. Higher density means closer stacking of graphene sheets, fewer internal pores, and stronger interlayer interaction, which optimizes conduction pathways and improves structural stability, leading to higher thermal conductivity and greater tensile strength. These results further confirm that there is a profound intrinsic correlation between the performance system of the films (including thermal conductivity, mechanical properties, electrical properties, and thermal stability) and their microscopic morphology and structural composition.
In conclusion, the microscopic morphology and structural characteristics of the composition of graphene heat dissipation films interact and exert a synergistic effect, jointly shaping their macroscopic properties in terms of thermal conductivity, mechanics, and electricity. In this study, the multi-dimensional structure-property correlation of graphene heat dissipation films is clarified, which is of great significance for guiding the structural optimization and performance regulation of such films, and lays a solid foundation for their wide application in thermal management fields such as high-power electronic equipment.