Structure and microwave-absorbing properties of Fe-particle containing alumina prepared by micro-arc discharge oxidation

Alumina films containing Fe particles were produced on aluminum alloy substrates by micro-arc oxidation with additive Fe particles in the electrolyte. The permittivity-frequency and permeability-frequency properties were determined in the microwave frequency regime of 6.5-18 GHz by vector network analysis. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF) were employed to investigate the microstructures and compositions. Our results show that about 16.16 wt.% Fe particles are embedded in the alumina films and the acquired complex permittivity and permeability values match the microwave frequency. When the matching thickness is 2 mm, the minimum RL values are - 10.5 dB at 9.6 GHz and - 9.1 dB at 16.3 GHz. The results suggest a new design of microwave absorbers based on electromagnetic wave-absorbing materials that eliminate the use of a mixture of agglutinants in the preparation. (c) 2005 Elsevier B.V. All rights reserved.