RESUMO
With the rapid spread of wireless technologies and increasing electromagnetic energy, electromagnetic waves (EMW) have become a severe threat to human health. Therefore, minimizing the harmful effects of electromagnetic wave radiation is possible through the development of high-efficiency EMW absorption coatings. The aim of this work was to generate microwave absorbance coatings containing synthesized nano-CuFe2O4 and nano-CaFe2O4. Firstly, nano-CuFe2O4 and nano-CaFe2O4 were synthesized using the sol-gel method. Then, their structure, electrical, dielectric, and magnetic properties were investigated to find out the possibility of using these materials in high-frequency applications (e.g., microwave absorbance coatings). After that, two dosages (2.5 wt% and 5 wt%) of nano-CuFe2O4 and nano-CaFe2O4 were incorporated into epoxy resin to prepare modified epoxy resin as microwave coatings. The dielectric studies show that the AC conductivity of the prepared samples is high at high frequencies. Additionally, the magnetic properties reveal a low coercivity value, making these samples suitable for high-frequency devices. The microwave results illustrate that adding nano-ferrites with high content enhances the absorption characteristics of the tested films. The results showed that the two films have two absorption bands with RL < -10 dB ranging from 10.61 to 10.97 GHz and from 10.25 to 11.2 GHz. The minimum return loss achieved for the two cases is -13 and -16 dB, respectively. Indicating that the film coated with CuFe has a better absorption value than the one coated with CaFe.
