Ultra-light 3D bamboo-like SiC nanowires felt for efficient microwave absorption in the low-frequency region

Nonmagnetic ceramics are ideal microwave absorbing materials used in high-temperature and oxidizing envi-ronments. However, low-frequency absorbing properties of this material are rarely reported because low -frequency absorbing requires nonmagnetic materials to have much higher permittivity. In this research, a se-ries of three-dimensional architectures formed by SiC nanowires with different microstructures felt were fabri-cated to address this issue. The morphology of the SiCnw (linear, bamboo-shaped, and worm-like) dominated by the VLS growth mechanism can be manipulated by the silicon vapor concentration, which is governed by the vaporization temperature of the mixed silicon source (Si and SiO2) in different sintering processes. The spon-taneously overlapped bamboo-shaped SiC nanowires in these felt enhance the permittivity and conductivity loss and produce multiple scattering effects on the incident EM waves, thus increasing the low-frequency wave ab-sorption ability. The RLmin of the bamboo-shaped SiCnw felt reaches-44.3 dB at 3.85 GHz with the corre-sponding EAB of 0.64 GHz (3.6-4.24 GHz) at a thickness of 3.5 mm. The density of the SiCnw felt is as low as 0.022 g/cm3 due to the high porosity (99.3%) of 3D networks, which fulfills lightweight requirements and highly efficient electromagnetic wave absorption.