Flexible FeSi/SiC ultrathin hybrid fiber mats with designable microwave absorption performance.

Flexible FeSi/SiC ultrathin fiber mats have been fabricated by electrospinning and high temperature treatment (1400 °C) using polycarbosilane (PCS) and ferric acetylacetonate (Fe(acac)) as precursors. The crystallization degree, flexibility, electrical conductivity, dielectric loss and microwave absorption properties of the hybrid fibers have been dramatically enhanced by the introduction of Fe. FeSi nanoparticles with a diameter around 500 nm are embedded in SiC fibers. As the FeSi content increases from 0 to 6.5 wt%, the related saturation magnetization ( ) values increase from 0 to 8.4 emu g, and the electrical conductivity rises from 7.9 × 10 to 3.1 × 10 S cm. Moreover, the flexibility of FeSi/SiC hybrid fiber mats is greatly improved and remains intact after 500 times 180°-bending testing. Compared with pure SiC fibers, the FeSi/SiC hybrid fibers process higher dielectric and magnetic loss, which would be further advanced as more FeSi phase is introduced. At the optimal FeSi content of 3.8 wt%, the FeSi/SiC fibers/silicon resin composite (5 wt%) exhibits minimal reflection loss (RL) of -22.5 dB at 16.5 GHz and 2.5 mm thickness with a wide effective absorption bandwidth (EAB, RL < -10 dB) of 8.5 GHz. The microwave absorption performance can be further promoted by multi component stacking fiber mat composites which contain both low and high FeSi content layers. Furthermore, the position of the microwave absorption bands can also be simply manipulated by designing the stacking components and structure.