Science and Technology on Thermostructural Composite Materials Laboratory and State Key Laboratory of Solidification Processing, Northwestern Polytechnical University , 710072 Xi'an, China.
ACS Appl Mater Interfaces. 2017 Aug 30;9(34):28844-28858. doi: 10.1021/acsami.7b05382. Epub 2017 Aug 21.
SiC/SiN composite nanofibers with in situ embedded graphite, which show highly efficient electromagnetic (EM) wave absorption performance in gigahertz frequency, were prepared by electrospinning with subsequent polymer pyrolysis and annealing. By means of incorporating graphite and SiN into SiC, the EM wave absorption properties of the nanofibers were improved. The relationship among processing, fiber microstructure, and their superior EM wave absorption performance was systematically investigated. The EM wave absorption capability and effective absorption bandwidth (EAB) of nanofibers can be simply controlled by adjusting annealing atmosphere and temperature. The nanofibers after annealing at 1300 °C in Ar present a minimum reflection loss (RL) of -57.8 dB at 14.6 with 5.5 GHz EAB. The nanofibers annealed in N at 1300 °C exhibit a minimum RL value of -32.3 dB at a thickness of 2.5 mm, and the EAB reaches 6.4 GHz over the range of 11.3-17.7 GHz. The highly efficient EM wave absorption performance of nanofibers are closely related to dielectric loss, which originated from interfacial polarization and dipole polarization. The excellent absorbing performance together with wider EAB endows the composite nanofibers potential to be used as reinforcements in polymers and ceramics (SiC, SiN, SiO, AlO, etc.) to improve their EM wave absorption performance.
采用静电纺丝结合聚合物热解和退火工艺，制备了原位嵌入石墨的 SiC/SiN 复合纳米纤维，在吉赫兹频率范围内表现出高效的电磁波（EM）吸收性能。通过将石墨和 SiN 掺入 SiC 中，改善了纳米纤维的电磁波吸收性能。系统研究了处理、纤维微观结构与优异电磁波吸收性能之间的关系。通过调整退火气氛和温度，可以简单地控制纳米纤维的电磁波吸收能力和有效吸收带宽（EAB）。在 Ar 中于 1300°C 退火后的纳米纤维在 14.6 GHz 时具有最小的反射损耗（RL）值为-57.8 dB，在 5.5 GHz 的有效吸收带宽为 5.5 GHz。在 N 中于 1300°C 退火后的纳米纤维在 2.5mm 厚度时具有最小 RL 值为-32.3 dB，在 11.3-17.7 GHz 的范围内 EAB 达到 6.4 GHz。纳米纤维的高效电磁波吸收性能与其介电损耗密切相关，介电损耗源于界面极化和偶极子极化。优异的吸收性能和更宽的 EAB 使复合纳米纤维有望用作聚合物和陶瓷（SiC、SiN、SiO、AlO 等）的增强体，以提高其电磁波吸收性能。
