Enhanced electromagnetic wave absorbing properties of Si‐O‐C ceramics with in‐situ formed 1D nanostructures

Abstract

Abstract The Si‐O‐C ceramics were prepared by polymer‐derived ceramic method using polysiloxane/FeCl 3 as precursor with the FeCl 3 content of 1.0 wt%. The microstructure, dielectric properties, and electromagnetic wave (EMW) absorbing properties in X band of the Si‐O‐C ceramic were investigated. It was found that the pyrolysis temperature has a great influence on the amount of in‐situ formed CNTs and the transformation from CNTs to 1D SiC nanostructures. With the temperature rising from 1000 to 1500°C, the SiC formed with various morphologies including SiC microspheres, needle‐like SiC, and SiC nanowires which were transformed from CNTs. The EMW absorbing properties were dramatically improved when the pyrolysis temperature raised to 1500°C; the minimum reflection loss (RL) was −58.37 dB of sample with a thickness of 2.95 mm at 10.11 GHz, and the absorbing band (RL ≤−20 dB) of sample at a thickness of 3.0 mm covers 3.8 GHz (8.2‐12.0 GHz), which means more than 99% of the EMW were absorbed. The enhancement of EMW absorbing properties of bulk Si‐O‐C ceramics was attributed to the interfacial polarization induced by in‐situ heterogeneous nanostructures with complex interfaces.