Cyanate ester resin filled with graphene nanosheets and CoFe2O4-reduced graphene oxide nanohybrids as a microwave absorber

Novel composites composed of CoFe2O4 spheres and reduced graphene oxide (RGO) were synthesized by using a facile hydrothermal route in combination with calcination at 550 °C. A series of characterization results indicate that the as-prepared CoFe2O4 spheres with relatively uniform sizes are homogeneously distributed on RGO layers. As absorbing materials, absorption properties of the graphene sheets (GNSs)/RGO-CoFe2O4 nanohybrid/cyanate ester resin (CE) composites were investigated in the measured microwave range of X-band (8.2-12.4 GHz). It can be found that the maximum reflection loss of the GNSs/RGO-CoFe2O4 nanohybrid/CE composites can reach −21.8 dB at 11.8 GHz with a thickness of 1.25 mm, and the frequency bandwidth less than −10 dB is from 9.6 to 12.4 GHz. The enhanced electromagnetic absorption property of the composites was attributed to the better impedance matching. While, when the GNSs loading is 5 wt%, high permittivity of the composites is harmful to the impedance match and results in strong reflection and weak absorption. Therefore, the GNSs/RGO-CoFe2O4 nanohybrid/CE composites, with excellent electromagnetic absorption properties and wide absorption bandwidth, can be obtained via adjusting the filler content to meet wide applications in the aerospace industry.