Enhanced microwave absorption performance of FeAl flakes by optimizing the carbon nanotube coatings.

FeAl is a good magnetic loss absorber for microwave absorption. However, due to the relatively high density and poor impedance matching ratio, the potential of FeAl cannot be fully released. Herein, a dielectric loss absorber of carbon nanotubes (CNTs) is coupled with FeAl to form FeAl/CNTs composite absorbers. CNTs are randomly tangled and coated on the surface of the FeAl flakes, forming a connecting conductive network. By carefully tuning the content of CNTs, the optimized FeAl/CNTs composite absorber with 1.5% of CNTs can combine both magnetic loss and dielectric loss mechanisms, thus achieving an impedance matching ratio close to 1 while keeping strong attenuation for enhanced microwave absorption. As a result, an effective absorption bandwidth (RL ≤ -10 dB) of 4.73 GHz at a thickness of 2 mm is achieved.