Nano-turbostratic carbon-decorated SiOC ceramic aerogels with ultra-broadband electromagnetic wave absorption properties

Abstract

As thermal insulation-electromagnetic wave absorption (EMA) integrated materials, ceramic aerogels’ thermal properties have been extensively investigated, whereas their EMA properties have not. In this work, nano-turbostratic carbon-decorated SiOC ceramic aerogels were fabricated by pyrolyzing polysiloxane modified with divinylbenzene (DVB). Investigations were conducted into the effects of DVB content on the compositions, microstructures, and EMA properties of SiOC ceramic aerogels. Our research uncovered that SiOC ceramic aerogels contained ultrafine nano-turbostratic carbons (around 5 nm), resulting in abundant interface and defect polarizations. SiOC ceramic aerogels with excellent EMA properties at both small (<5 mm) and large (up to 40 mm) thicknesses were obtained by adjusting the DVB content. The reflection loss and effective absorption bandwidth of SiOC ceramic aerogels were -65.6 dB and 6 GHz at a sample thickness of 2.45 mm, while the effective absorption bandwidth widened to 11.2 GHz at 40 mm. The EMA mechanism of SiOC ceramic aerogels was discussed.