Enhanced microwave absorption performance of Fe₃Al flakes by optimizing the carbon nanotube coatings

Fe₃Al is a good magnetic loss absorber for microwave absorption. However, due to the relatively high density and poor impedance matching ratio, the potential of Fe₃Al cannot be fully released. Herein, a dielectric loss absorber of carbon nanotubes (CNTs) is coupled with Fe₃Al to form Fe₃Al/CNTs composite absorbers. CNTs are randomly tangled and coated on the surface of the Fe₃Al flakes, forming a connecting conductive network. By carefully tuning the content of CNTs, the optimized Fe₃Al/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.