Attapulgite coated polycrystalline iron fibers composites with light weight feature and enhanced microwave absorption properties

In this study, attapulgite coated polycrystalline iron fibers (ATP/IF) composites were prepared by layer-by-layer electrostatic self-assembly technology and aligned ATP/IF composite were prepared by shear-force. The complex permittivity decreases from 35 to 20 and permeability decreases from 1.3 to 1.15 at 2.6 GHz for ATP/IF-1 composite. Anisotropy electromagnetic properties were achieved by aligned ATP/IF composites. The microwave absorption properties show that broader bandwidth and better absorption efficiency were obtained by ATP/IF composite (the minimum RL values decrease to −35 dB, the absorption bandwidths with RL below −5 dB is 8.8 GHz at thickness of 1.8 mm for ATP/IF-4 composite), and the microwave absorption performance was further enhanced by aligned ATP/IF-1-A composite (the bandwidth increases to 7.5 GHz at thickness of 1.2 mm). Double-layer ATP/IF composite was designed and the microwave absorption performance show that broader bandwidth and better efficiency can obtained by adjusting the impedance matching characteristics and the absorption characteristics of ATP/IF composite. When d₁ = 1.5 mm, d₂ = 0.5 mm, the absorption bandwidth is 7.0 GHz from 7.0 to 14 GHz and the minimum RL value reach about - 30 dB, showing higher absorption efficiency and wider bandwidth compared to single-layer aligned ATP/IF composite. Lightweight absorbers with enhanced microwave absorption performance were obtained under a lower content of 40 wt% due to the ATP coating on the surface of IF and alignment of ATP/IF composites.