Structure regulation and microwave absorption property of SiCN ceramic aerogels produced by catalytic pyrolysis

Abstract

In the present work, polymer-derived SiCN ceramic aerogels (PDCA-SiCN) were fabricated via a combined sol-gel/freeze drying/polymer precursor conversion method. The microstructure of PDCA-SiCN was studied by regulating the synthesis temperature and time during the sol-gel process. PDCA-SiCN showed a unique three-dimensional network structure, and the specific surface area and pore size of PDCA-SiCN prepared at 150 °C for 20 h were 134 g/m2 and 18 nm, respectively. To assess the electromagnetic wave absorption (EMA) properties of PDCA-SiCN, the materials were uniformly blended with common paraffin, and the influence of PDCA-SiCN/paraffin ratio on the EMA properties was also investigated. The sample with a PDCA-SiCN/paraffin ratio of 20:80 exhibited the best EMA performance, with a minimum reflection loss (RL) of −43.37 dB at 7.6 GHz and electromagnetic absorption bandwidth of 3.8 GHz, which correspond to an absorption of 99.99 % of the electromagnetic waves. The excellent EMA properties of PDCA-SiCN could be attributed to a synergistic effects of good impedance matching, multiple reflections and high dielectric loss.