石墨烯和六方氮化硼纳米片薄膜的制备和导热性能研究

发布时间：2018-06-03 11:28

本文选题：石墨烯 + 氮化硼纳米片　；参考：《安徽理工大学》2017年硕士论文

【摘要】：石墨烯作为先进二维材料,具有很好的物理化学性能。由于其比表面积大,机械伸缩性良好,导热性高,在新材料领域引起了越来越多的关注。六方氮化硼纳米片(BNNS),与石墨烯具有相似的结构。石墨烯导热性能优越且导电性能好,而BNNS却是很好的电绝缘材料,介电常数为2-4.8。在电子封装和高功率电子学中的热传递耗散材料中的应用前景广阔,但通过六方氮化硼(h-BN剥离制备BNNS存在各种各样的问题。本论文主要包括三个方面:(1)石墨烯厚度对相应的石墨烯薄膜的导热性能和介电性能的影响;(2)发明了以熔融碱机械剥离氮化硼纳米片(BNNS)的方法,并制备了出上下两层为石墨烯纳米片,中间为BNNS的三明治复合材料薄膜。并研究对比了三明治薄膜与石墨烯薄膜的导热性能的差异;(3)采用抽滤方法制备了独立的BNNS薄膜,并研究了 BNNS在高分子材料聚酰亚胺中的应用。研究表明:(1)厚度越大的石墨烯纳米片对应的石墨烯薄膜水平方热传导能力越高和导电能力越强。厚度为7 nm的GNP-7薄膜的导热系数高达149.2 W/mK,约为GNP-3(厚度为3 nm)和GNP-5(厚度为5 nm)的7倍。此外,GNP-7冷压后导热系数又提高了 25%到187.4 W/mK;(2)研究了一种利用熔融碱和超声剥离技术制备六方氮化硼纳米片的方法,这种BNNS剥离方法不仅工艺简单、处理原料廉价易得、对设备要求低、对环境毒性小、且便于大规模生产,可大大降低产品成本,而且产率高达19%,高于迄今为止所报道的大多数液相剥离方法。同时剥离制备的BNNS的粒径为0.5-2.5 um,厚度为0.5-7 nm,且表面修饰有羟基。同时采用简单的真空抽滤方法,制备了石墨烯-氮化硼纳米片-石墨烯(G-BNNS-G)的三明治薄膜。通过对其导热性能分析,G-BNNS-G薄膜在水平方向导热系数达53.09 W/mK,较GNP-3薄膜(21.5 W/mK)高;(3)独立的BNNS薄膜在水平方向导热系数高达58 W/mK,聚酰亚胺(PI)中加入7 wt%的BNNS时,BNNS/PI复合材料垂直方向的导热系数为0.441 W/mK而水平方向的导热系数达到2.946 W/mK,与纯PI薄膜相比,水平方向导热系数增加了1078%,但垂直方向仅增加76%,具有明显的各向异性。
[Abstract]:As an advanced two-dimensional material, graphene has good physical and chemical properties. Because of its large specific surface area, good mechanical scalability and high thermal conductivity, it has attracted more and more attention in the field of new materials. The structure of hexagonal boron nitride nanocrystalline (BNNSN) is similar to that of graphene. Graphene has excellent thermal conductivity and good conductivity, but BNNS is a good electrical insulating material with a dielectric constant of 2-4.8. The applications in electronic packaging and high power electronics heat transfer dissipative materials are promising, but there are various problems in the preparation of BNNS by hexagonal boron nitride h-BN peeling. This thesis mainly includes three aspects: the influence of the thickness of graphene on the thermal conductivity and dielectric properties of the corresponding graphene thin films. The method of mechanical stripping of boron nitride nanocrystalline (BNNSs) with molten alkali was invented in this paper. A sandwich composite film with two layers of graphene nanocrystalline and BNNS in the middle was prepared. The difference of thermal conductivity between sandwich film and graphene film was compared. The independent BNNS thin film was prepared by filtration method and the application of BNNS in polymer polyimide was studied. The results show that the higher the thickness of graphene nanocrystals, the higher the horizontal thermal conductivity and conductivity of graphene films. The thermal conductivity of GNP-7 thin films with thickness of 7 nm is as high as 149.2 W / mK, which is about 7 times that of GNP-3 (thickness of 3 nm) and GNP-5 (thickness of 5 nm). In addition, the thermal conductivity of GNP-7 has been increased by 25% to 187.4 W / mKK ~ (2) after cold pressing. A method of preparing hexagonal boron nitride nanocrystals using molten alkali and ultrasonic stripping technology has been studied. This BNNS stripping method is not only simple in process, but also cheap in processing raw materials. Because of its low requirements for equipment, low toxicity to the environment, and convenient for mass production, the cost of the product can be greatly reduced, and the yield is as high as 19 percent, which is higher than most liquid stripping methods reported so far. The diameter and thickness of the BNNS were 0.5-2.5 um. the thickness was 0.5-7 nm, and the surface was modified with hydroxyl groups. At the same time, the sandwich films of graphene-boron nitride nanocrystalline-graphene G-BNNS-G were prepared by a simple vacuum filtration method. Thermal conductivity analysis of G-BNNS-G thin films with horizontal thermal conductivity of 53.09 W / mK, 21.5 W / mK higher than that of GNP-3 thin films.) the horizontal thermal conductivity of BNNS films is as high as 58 W / mK, and 7 wt% BNNS is added to the BNNS films. The thermal conductivity in the vertical direction is 0.441 W/mK, and the thermal conductivity in the horizontal direction is 2.946 W / mK. compared with the pure Pi film, The thermal conductivity in the horizontal direction increases by 1078, but in the vertical direction only increases by 76, with obvious anisotropy.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2

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