Department of Materials Processing, Graduate School of Engineering , Tohoku University , Sendai 980-8579 , Japan.
State Key Laboratory of High Performance Ceramics and Superfine Microstructure , Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050 , China.
ACS Appl Mater Interfaces. 2018 Nov 14;10(45):39245-39256. doi: 10.1021/acsami.8b12933. Epub 2018 Oct 30.
Ceramic composites with good electrical conductivity and high strength that can provide electromagnetic interference (EMI) shielding are highly desirable for the applications in harsh environment. In this study, lightweight, highly conductive, and strong mullite composites incorporated with reduced graphene oxide (rGO) are successfully fabricated by spark plasma sintering at merely 1200 °C using the core-shell structured γ-AlO@SiO powder as a precursor. The transient viscous sintering induced by the γ-AlO@SiO precursor not only prohibits the reaction between mullite and rGO by greatly reducing the sintering temperature, but also induces a highly anisotropic structure in the rGO/mullite composite, leading to an extremely high in-plane electrical conductivity (696 S m for only 0.89 vol % of rGO) and magnitude lower cross-plane electrical conductivity in the composites. As a result, very large loss tangent and EMI shielding effectiveness (>32 dB) can be achieved in the whole K band with extremely low rGO loading (less than 1 vol %), which is beneficial to maintain a good mechanical performance in ceramic matrix composites. Accordingly, the rGO/mullite composites show greatly improved strength and toughness when the rGO content is not high, which enables them to be applied as highly efficient EMI shielding materials while providing excellent mechanical performance.
具有良好导电性和高强度的陶瓷复合材料，可以提供电磁干扰（EMI）屏蔽，因此非常适合在恶劣环境下使用。在这项研究中，采用核壳结构的γ-AlO@SiO 粉末作为前驱体，通过火花等离子烧结在 1200°C 以下成功制备了轻质、高导电性和高强度的莫来石复合材料，其中掺入了还原氧化石墨烯（rGO）。γ-AlO@SiO 前驱体的瞬态粘性烧结不仅通过大大降低烧结温度来阻止莫来石和 rGO 之间的反应，而且还在 rGO/莫来石复合材料中诱导出各向异性结构，从而使复合材料的面内电导率极高（仅 0.89 体积%的 rGO 时，电导率为 696 S m），而面外电导率则大大降低。因此，在整个 K 波段可以实现非常大的损耗正切和 EMI 屏蔽效能（>32 dB），且 rGO 的负载量（小于 1 体积%）非常低，这有利于保持陶瓷基复合材料的良好机械性能。因此，当 rGO 含量不高时，rGO/莫来石复合材料的强度和韧性得到了显著提高，这使它们能够作为高效 EMI 屏蔽材料使用，同时提供优异的机械性能。
