Additive manufacturing of nanocellulose/polyborosilazane derived CNFs-SiBCN ceramic metamaterials for ultra-broadband electromagnetic absorption

Electromagnetic absorption materials that possess efficient absorption performance and broad absorption bandwidth are needed to combat the electromagnetic interference (EMI). SiBCN ceramic-based metamaterials modified with defect-rich carbon nanofibers (CNFs) were developed by combining the additive manufacturing technique and polymer derived ceramic route. Meta-structures were patterned by additive manufacturing of preceramic polymer and followed by thermolysis of the green bodies. Defect-rich CNFs were in-situ generated by thermolysis of nanocellulose introduced into the preceramic green bodies. When the content of cellulose is 6.0 wt% and the annealing temperature is 1200 °C, the real and imaginary part of permittivity can reach as high as 17.0 and 7.0, respectively. Cole-Cole circle plots indicates that the CNFs-SiBCN ceramics possess strong polarization capability due to the defect-rich structure of CNFs. At the thickness of 1.8 mm, the minimal reflection loss (RLmin) can reach −20.0 dB while the effective absorption bandwidth reached 2.85 GHz. Through multi-scale (nano and macro) designing, a simulated ultra-broad effective absorption bandwidth of 32.4 GHz from 7.6 GHz to 40 GHz was achieved, where the RLmin reached −46.0 dB at the frequency of 26.8 GHz. This work finds innovative route for the development of ceramic-based broadband electromagnetic absorption materials and new application for the polymer derived ceramics.