Single-source-precursor synthesis and electromagnetic properties of novel RGO-SiCN ceramic nanocomposites

Single-source-precursors (SSPs) have been synthesized through chemical modification of poly(methylvinyl)silazane (HTT 1800) with graphene oxide (GO) via an amidation reaction catalyzed by ZnCl₂. With the formation of an SSP, the restacking of GO was effectively prevented by the HTT 1800 grafted at the surface of GO. After pyrolysis of warm-pressed green bodies comprising the SSP, GO-HTT 1800, monolithic silicon carbonitride (SiCN) ceramic nanocomposites containing in situ thermally reduced graphene oxide (RGO), namely RGO-SiCN, were successfully prepared. The resultant RGO-SiCN nanocomposites possess versatile electromagnetic (EM) properties ranging from EM absorbing to shielding behavior. With 2.5 wt% GO in the feed, the final RGO-SiCN nanocomposite exhibits an outstanding minimal reflection coefficient (RC_min) of -62.1 dB at 9.0 GHz, and the effective absorption bandwidth reaches 3.0 GHz with a sample thickness of 2.10 mm. With the same GO content, the resultant RGO-SiCN nanocomposite prepared by mechanical blending exhibits a far inferior RC_min of -8.2 dB. This finding strongly supports the advantage of the developed SSP route suitable for the fabrication of RGO-SiCN nanocomposites with significantly enhanced EM properties. With 12.0 wt% GO content in the feed, the obtained RGO-SiCN nanocomposite reveals an excellent shielding effectiveness of 41.2 dB with a sample thickness of 2.00 mm.