Mechanical, dielectric and microwave absorption properties of FeSiAl/Al2O3 composites fabricated by hot-pressed sintering

FeSiAl/Al2O3 composites were fabricated by hot-pressed sintering to evaluate the mechanical, dielectric and microwave absorption properties. The results show that the flexural strength of the composites increases with the increase of FeSiAl content, while the density and micro-hardness exhibit a downward tendency. The complex permittivity increases with increasing FeSiAl content in the X-band, which is resulted from the enhanced interfacial polarization, relaxation loss and conductance loss. Meanwhile, a rapid enhancement of complex permittivity for the composite with 10 wt.% FeSiAl is achieved due to the formation of conductive clusters and enhanced conductance loss. By calculating the reflection loss, the composite with 5 wt.% FeSiAl possesses the effective absorption bandwidth (<-10 dB) 1.9 GHz in 9.1-11.0 GHz and the strong absorption peak of −34.2 dB is achieved at 9.4 GHz when the thickness is 1.9 mm due to its best impedance matching and appropriate electromagnetic wave attenuation.