Effects of BaTiO3 and FeAlSi as fillers on the magnetic, dielectric and microwave absorption characteristics of the epoxy-based composites

A systematic study was carried out on the magnetic, dielectric and microwave absorption properties of the two-phase FeAlSi/epoxy and three-phase FeAlSi/BaTiO3/epoxy composites through experimental and simulation method. A percolation effect was observed in the dielectric, but not in the magnetic behavior of the FeAlSi/epoxy composites when the FeAlSi content was high. The 2D modeling shows that the high electric energy density is responsible for the high permittivity near the percolation threshold (49 vol%). On the other hand, the permeability of the composites matches well with the effective medium theory model (EMT), indicating that the permeability of FeAlSi/epoxy composite is more associated with the filler size and shape. Theoretical calculations show that the increment of the FeAlSi and BaTiO3 loading, as well as the thickness will cause the absorption peak position to shift to low frequencies. The microwave absorption of these composites can be mainly attributed to the dielectric loss and magnetic loss.