Effect of morphology on electromagnetic properties and microwave absorption properties of carbonyl iron powder

Flake carbonyl iron was prepared by high-energy ball milling. The changes of morphology and structure of carbonyl iron powder before and after ball milling and the effects of morphology on electromagnetic parameters, reflectivity and microwave absorption properties were studied. The results show that after ball milling, carbonyl iron powder changes from 2um~5um globular to about 2um~10um flake, and the structure does not change. After ball milling, the flake particles are easy to overlap, the conductivity is improved, and the complex permittivity and permeability are significantly improved. The microwave absorption performance of the tested coating (1mm) is basically consistent with the calculated reflectivity. The absorption bandwidth of globular carbonyl iron powder less than -7.5dB is 11.0GHz~18.0GHz, and the absorption peak frequency is 15.1GHz. The absorption bandwidth of flake carbonyl iron powder less than -7.5dB is 7.0GHz~12.5GHz, and the absorption peak frequency is 10.5GHz.