Science and Technology on Thermostructural Composite Materials Laboratory , Northwestern Polytechnical University , Xi'an 710072 , China.
ACS Appl Mater Interfaces. 2019 Feb 6;11(5):5364-5372. doi: 10.1021/acsami.8b20023. Epub 2019 Jan 29.
The fabrication of a sandwich-like composite that consists of reduced graphene oxide (RGO) and SiN ceramic (RGO/SiN) was achieved through the combination of modified freeze-drying approach and chemical vapor infiltration process. Due to a hierarchical structure and a high ratio of I/ I (1.27), the RGO/SiN exhibits an unprecedented high polarization relaxation loss (PRL), which accounts for 32% of the whole dielectric loss. The outstanding PRL endows the RGO/SiN composites with unique temperature-independent dielectric properties and electromagnetic (EM) wave absorption performance. Even at a low absorbent content of only 0.16 wt %, the effective absorption bandwidth of RGO/SiN composites can cover the whole X-band (8.2-12.4 GHz) at broad sample thicknesses ranging from 4.3 to 4.6 mm and temperatures ranging from 323 to 873 K. The mechanism for the enhancement of PRL and conductive loss was explicitly investigated. The outstanding absorption performance toward EM waves indicated that the resultant porous RGO/SiN composite can be a promising candidate for the applications under elevated temperature.
通过改进的冷冻干燥法和化学气相渗透工艺的结合，制备了由还原氧化石墨烯（RGO）和 SiN 陶瓷（RGO/SiN）组成的类三明治复合材料。由于具有分级结构和较高的 I/ I（1.27）比值，RGO/SiN 表现出前所未有的高极化弛豫损耗（PRL），占整个介电损耗的 32%。出色的 PRL 使 RGO/SiN 复合材料具有独特的温度无关介电性能和电磁波（EM）波吸收性能。即使在仅为 0.16wt%的低吸收剂含量下，RGO/SiN 复合材料的有效吸收带宽在 4.3 至 4.6mm 的宽样品厚度和 323 至 873K 的宽温度范围内可覆盖整个 X 波段（8.2-12.4GHz）。明确研究了 PRL 和导电损耗增强的机理。对电磁波的优异吸收性能表明，所得多孔 RGO/SiN 复合材料有望成为高温应用的候选材料。
