Preparation and characterization of polymer-derived SiC ceramic aerogels toward excellent electromagnetic wave absorption properties

SiC ceramic aerogels (CAs) with lightweight and high specific surface area have been synthesized through a sol-gel/freeze-drying technique combined with a polymer-derived ceramics (PDCs) method. The phase composition and micro-structure of the as-prepared SiC CAs were systematically characterized by a series of techniques. The results showed that the SiC CAs possess three-dimensional (3-D) network porous structure with low density, and high porosity. Meanwhile, the formation mechanism and evolution process of the SiC CAs were discussed. As applications, the electromagnetic wave (EMW) absorption properties were characterized and showed that the optimal RL can reach -26.5 dB at 11.98 GHz with thickness of 2.5 mm and its EAB is 5.4 GHz in the range of 9.6-15.0 GHz. In addition, a possible EMW absorption mechanism was also explored. The excellent EMW absorption properties endow the as-prepared SiC CAs promising materials employed in the fields of EMW absorption applications.