Effect of morphology on microwave absorption properties of carbonyl iron/Fe-Si-Cr composites

Abstract:

To effectively improve the electromagnetic absorption strength and effective absorption bandwidth of absorbing materials, the spherical Fe-Si-Cr was flattened by ball milling, and carbonyl iron powder (CIP) with different morphologies was compounded with Fe-Si-Cr by mechanical blending method. The effects of mass ratio on the electromagnetic parameters and microwave absorption properties of the composites were studied. Experimental results show that high aspect ratio could improve the dielectric constant and permeability of the material, and make the reflectivity peak shift to low frequency. The low-frequency absorption properties of flaky Fe-Si-Cr and CIP were better than those of spherical particles. Among the composite materials prepared in the experiment, the maximum reflection loss of sample I was -45.92 dB, and the effective absorption bandwidth was 1.5 GHz. The maximum reflection loss of sample L was -22.11 dB, and the effective absorption bandwidth was greater than 6.2 GHz. The morphology of the absorber had a significant influence on the electromagnetic absorption performance of the material. After compounding different morphologies of CIP and Fe-Si-Cr according to different proportions, absorbers with excellent performance at different frequencies were obtained. The impedance matching function could theoretically predict the thickness and frequency of the absorber corresponding to the peak of the reflection loss. Compared with single-layer absorbing materials, the effective absorption bandwidth of double-layer absorbing materials was larger, and the absorbers with excellent absorbing properties at different frequencies could be obtained by changing the thickness of matching layer and absorption layer, which can easily meet the requirements of new absorbing materials of “thin, light, wide, and strong”.