Electromagnetic and microwave absorbing properties of raw and milled FeSiCr particles

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 (epsilon' - j epsilon '') and permeability (mu' - j mu '') 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 30wt. % of FeSiCr/epoxy absorbers with 2mm thickness, the calculated reflection loss reaches -25 dB at 13.0GHz for raw flaky powder, -40 dB at 11.4GHz for the re-milled FeSiCr powder with higher aspect ratios. (C) 2014 AIP Publishing LLC.