Enhancing broadband and intense microwave absorption properties of flaky FeSiCr powder by coating SiO2

Flaky [email protected]2 composites with broadband and intense absorption were successfully synthesized by modified Stöber method. The phase, microstructure and morphology of flaky [email protected]2 composites were investigated by XRD, FT-IR, SEM and TEM, confirming the successful preparation of SiO2 coating. The thermal behavior of flaky [email protected]2 composites was analyzed by TGA/DSC. The results showed that the oxidation resistance of the coated FeSiCr powder was promoted. The electromagnetic wave absorption properties of samples with different contents of tetraethyl orthosilicate (TEOS) were systematically investigated. The sample synthetized with 10 ml TEOS possesses the optimal absorption performance, which is attributed to the synergistic effect of magnetic loss and dielectric loss. The minimum reflection loss is −65.3 dB at 4.4 GHz. And the maximum effective absorption bandwidth is 6.0 GHz with only a 1.5 mm thickness. In particular, by controlling the thickness of the absorber, the effective absorption bandwidth can reach 13.3 GHz (2.9–16.2 GHz), covering the entire C and X bands. Thus, the flaky [email protected]2 composites can be used as high-performance microwave absorption materials.