Iron based carbon nanocomposites for electromagnetic wave absorber with wide bandwidth in GHz range

The electromagnetic wave absorption properties of resin compacts containing 40 vol. % composite powders of alpha-Fe/C(a), and Fe3C/C(a) were characterized in a frequency range of 0.05-26.5 GHz, according to a conventional reflection/transmission technique. The real part (epsilon'(r)) and the imaginary part (epsilon'(r)) of relative permittivity were constantly low in the 2-14 GHz (epsilon'(r) = similar to 12.4 and epsilon''(r) = similar to 0.6) for alpha-Fe/C(a) resin composites, and in the 1-26.5 GHz (epsilon'(r) = similar to 9.6 and epsilon''(r) = similar to 0.8) for Fe3C/C(a) ones. The imaginary part (mu''(r)) of relative permeability exhibited wide peaks in the 1-9 GHz range for alpha-Fe/C(a), and in the 2-26.5 GHz range for Fe3C/C(a) owing to their different magnetocrystalline anisotropy field values. Consequently, the resin compacts with 40 vol. % alpha-Fe/C(a), and Fe3C/C(a) powders provided good electromagnetic wave absorption performances (reflection loss < -20 dB) in ranges of 4.3-8.2 GHz, and 9-26.5 GHz over absorber thicknesses of 1.8-3.3 mm, and 1.0-2.4 mm, respectively.