基于还原氧化石墨烯与炭化硅的多孔电磁屏蔽薄膜及其多层结构

RGO@SiC porous films for multilayer electromagnetic shielding

  • 摘要: 轻质柔性的电磁屏蔽薄膜材料的开发具有重要的意义。本文报道了一种还原氧化石墨烯与炭化硅(RGO@SiC)的多孔状电磁屏蔽薄膜,其多孔结构由固态微波处理高效获得,仅3 s的处理便可高效还原氧化石墨烯,同时使薄膜厚度从大约20 μm增加至200 μm。当该薄膜的电磁屏蔽效能达到35.6 dB时,其反射效能仅为 2.8 dB。SiC晶须在薄膜中的添加有利于电磁波的多次反射、界面极化和介电衰减。进一步,将RGO@SiC多孔薄膜按照透过层到反射层的顺序叠加,构建多层复合薄膜,并采用多壁碳纳米管纸作为反射层。当多层结构厚度为1.5 mm时,最高电磁屏蔽效能达到75.1 dB,其中反射效能仍保持在2.7 dB。该多孔状RGO@SiC 薄膜可用于设计以吸收为主的电磁屏蔽多层封装材料或三明治结构的芯层。

     

    Abstract: Developing lightweight and flexible thin films for electromagnetic interference (EMI) shielding is of great significance. In this paper, RGO@SiC porous thin films for EMI shielding were prepared by chemical reduction of mixtures of graphite oxide (GO) and SiC whiskers with HI, followed by microwave irradiation for 3 s. A significant increase of the film thickness from around 20 to 200 μm and further reduction of GO were achieved due to formation of a porous structure via expansion of interlayer space of GO with gases released by heating in 3 s of solid phase microwave irradiation. The total shielding effectiveness (SET) and the reflective SE (SER) of the RGO@SiC porous thin films were altered by the GO/SiC mass ratio, which reached the highest SET of 35.6 dB while the SER was only 2.8 dB when the ratio was 12:3. The addition of SiC whiskers was critical for the multi-reflection, interfacial polarization and dielectric attenuation of EM waves. A multilayer composite with a gradient change from transmission to reflection of RGO@SiC porous films was constructed. The highest SET reached 75.1 dB with a SER of 2.7 dB for a film of a thickness of about 1.5 mm when the reflective side of the multilayer composite was stacked on a reflective buckypaper derived from multi-walled carbon nanotubes. We believe that the porous RGO@SiC thin films were promising for designing a multilayer or sandwich structure for EMI absorption in packaging or lining.

     

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