Lightweight microwave absorber from industrial waste fly ash cenosphere

Abstract

The present investigation demonstrates the microwave absorption property of magnetic alloy nanoparticle-coated solid industrial waste fly ash cenosphere (FAC). Here, cobalt iron (CoFe) alloy nanoparticles were chemically coated over FAC, and a composite matrix was made from these particles using epoxy resin. Surface morphology of both CoFe-FAC and epoxy/CoFe-FAC composites was studied. The dielectric loss and reflection loss (RL) of this polymer composite were studied by rectangular waveguide transmission line method. A 10 wt% CoFe-FAC-loaded epoxy composite shows an excellent microwave absorption property in the X-band (8.2–12.4 GHz). The most effective RL value −29 dB was obtained for epoxy/CoFe-FAC composite, whereas a pristine epoxy/FAC composite combination exhibits −12 dB RL under same condition. The thickness dependency of RL was also studied, and it indicates that the standard −10 dB RL can be obtained for epoxy/CoFe-FAC composite at a minimum thickness of 2 mm. The enhancement of dielectric loss, EM attenuation constant and loss factor with frequency was found to be responsible for the obtained RL.