Electromagnetic and microwave absorbing properties of raw and milled FeSiCr particles

Abstract

FeSiCr alloy (Fe: 90%, Si: 7.9%, and Cr: 2.1%) with pre-milled flaky shape was re-milled in a planetary ball-mill for 30 h. The complex permittivity (ε′−jε″) and permeability (μ′−jμ″) are measured by using the transmission/reflection method for two different aspect ratios of flake-shaped FeSiCr/epoxy composites for 30%, 40%, and 50% weight ratios. Dielectric loss tangent and magnetic loss tangent of re-milled FeSiCr powder show larger electromagnetic wave energy dissipation than those of the raw flaky FeSiCr powder. For 30 wt. % of FeSiCr/epoxy absorbers with 2 mm thickness, the calculated reflection loss reaches −25 dB at 13.0 GHz for raw flaky powder, −40 dB at 11.4 GHz for the re-milled FeSiCr powder with higher aspect ratios.