In situ synthesis of Fe3O4 coated on iron-based magnetic microwave absorbing materials and the influence of oxide magnetic materials on microwave absorption mechanism

Fe3O4 coated iron-based magnetic microwave absorbing materials were prepared by heat treatment in controllable oxygen atmosphere. The obtained core-shell microstructure improved the absorbing properties by enhancing the dielectric loss capability and optimizing the impedance matching. The effective absorption bandwidth (nearly reach -20 dB) of the composite material covers 3-18 GHz by adjusting the coating thickness from 1.5∼5.0 mm. The shell Fe3O4 improves the microwave absorbing properties and broadens the effective absorption frequency band of the iron-based material. In addition, the oxide layer improves the stability and environmental adaptability of the iron-based materials, which would provide reference idea for iron-based absorbing materials in industrial production.