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 (RCmin) 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 RCmin 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.