石墨烯微片尺寸对石墨烯纸热导率的影响

石墨烯热导率远高于传统金属薄膜等导热材料，可用作热扩散材料。石墨烯纸由石墨烯微片组装而成，石墨烯微片尺寸大小对其组装方式微观结构以及宏观导热性能等具有重要影响。采用溶液过滤自组装方法制备了分散均匀的氧化石墨烯纸，然后在Ar/H2气氛下对氧化石墨烯纸进行热还原处理，得到了石墨烯纸。结果表明，大尺寸石墨烯微片组成的石墨烯纸结构更加致密、结晶度更高；0.5 μm～3 μm和50 μm～100 μm的氧化石墨烯所制备的石墨烯纸的热导率分别为632.8 W/mK和683.7 W/mK，大尺寸石墨烯微片组成的石墨烯纸热导率提高了8%。
Graphene paper is a potential candidate for heat spreader because of its special thermal conductivity. As graphene paper is assembled by the graphene sheets, the size of graphene sheets has an important effect on assembly method, microstructure and thermal conductivity of the graphene paper. The influence of the size of graphene sheets on the microstructure and thermal property of graphene paper was studied. Firstly, the filtration-assembling method was used to fabricate graphene oxide paper. Then, the grapheme paper was obtained from the heat-reduced process of the graphene oxide paper under the Ar/H2 atmosphere. The SEM(scanning electron microscope) characterization result shows that the graphene paper with the bigger graphene sheet size is of higher density. The XRD(X-ray diffraction) characterization result also shows that the crystalline of the graphene paper is increased when the graphene sheet size is bigger. When graphene sheet size increased from the range of 0.3 μm～5 μm to that of 50 μm～100 μm, the thermal conductivity is about 632.8 W/mK and 683.7 W/mK respectively，which is increased by 8%. 