FeSiAl/ZnO-filled resin composite coatings with enhanced dielectric and microwave absorption properties

Composite coatings with resin matrix and hybrid fillers of FeSiAl and ZnO powders have been developed for their potential application as microwave absorbing coatings. The effects of FeSiAl and ZnO content on the complex permittivity, complex permeability and reflection loss (RL) of such composite coatings were studied in the frequency range of 8.2-12.4GHz (X-band). Compared with the complex permeability, the complex permittivity showed more dependence on the absorbent content and the permittivity values increase notably with increasing FeSiAl or ZnO content. Owing to the best impedance matching and appropriate electromagnetic attenuation, the composite coating filled with 35wt% FeSiAl and 20wt% ZnO powders exhibits the most desirable microwave absorption properties with the effective absorption bandwidth (<-10dB, >90% absorption) 3.5GHz in 8.6-12.1GHz and the strong absorption peak -40.5dB at 10.4GHz, when the thickness is 2.2mm. The results suggest that FeSiAl/ZnO-filled resin composite coatings could be qualified as good candidates for highly efficient and strong microwave absorbing coatings.