High temperature stable, amorphous SiBCN microwave absorption ceramics with tunable carbon structures derived from divinylbenzene crosslinked hyperbranched polyborosilazane

Currently, polymer-derived ceramics (PDCs) often achieve electromagnetic (EM) wave attenuation by in situ generation of nanocrystals . In this paper, amorphous monolithic siliconboron carbonitride (SiBCN) ceramics with outstanding microwave absorption property were prepared via pyrolysis of hyperbranched polyborosilazane crosslinked with divinylbenzene (DVB). The crosslinking of DVB increases the ceramic yield and the sp 2 carbon contents, which facilitates the formation of multiple ordered carbon structures and enhances the dielectric loss and microwave absorption property of ceramics. By regulating DVB content and pyrolysis temperature, the amorphous SiBCN ceramics with ordered carbon structures exhibit optimized microwave absorption performance with a minimum reflection coefficient (RC min ) of −54.24 dB and a maximum effective absorption bandwidth (EAB max ) of 3.15 GHz. Further, when the planar sample is tested using arch method, the practical RC min value is −14.86 dB at 14.46 GHz and the EAB max is up to 6.4 GHz (11.6 GHz–18 GHz). In addition, the amorphous SiBCN has excellent high temperature resistance, no mass change in nitrogen (N 2 ) and only 3.23% mass loss in air until 1400 °C. The high temperature stable, amorphous SiBCN microwave absorption ceramics provide a new strategy to the preparation of microwave absorption materials .