Intermetallic compound MxSi modified SiCO ceramic microspheres derived from precursor emulsion for electromagnetic wave absorption

Abstract

Novel intermetallic compound MxSi modified SiCO ceramic microspheres (SiCOM-ms) were successfully fabricated via the ceramic precursor emulsion method. These SiCOM-ms, with grain size ranging from 3 to 8 µm, had similar “chocolate ball” shape with numerous irregular protrusion on the surface. By adjusting the magnetic components in the precursor, different intermetallic compound MxSi phases were uniformly embedded in the SiCO ceramic matrix and further effectively promoted the formation of the SiC phase and graphited carbon phase. The complex interface structure in SiCOM-ms was derived from the in-situ generated MxSi, SiC, and graphited carbon nanocrystalline, which produced an enhanced interfacial polarization for electromagnetic wave absorption. It is worth mentioning that the SiCOM microspheres exhibit excellent electromagnetic wave absorption with the minimum reflection loss (RLmin) below − 60 dB, especially in the low frequency (2–8 GHz). Moreover, the RLmin of SiCOCo-ms could reach − 70.6 dB with the thickness of 4 mm, while the effective absorption bandwidth (EAB, RL<−10 dB) could reach 5.2 GHz at the thickness of 2.5 mm. As for the absorption mechanism, the impendence matching, multiple scattering, interfacial polarization and magnetic loss were all taken into consideration. This work is confident that the novel SiCOM-ms with outstanding electromagnetic performance can be considered ideal materials for electromagnetic absorbing field.