| With the development of modern science and technology, it brought serious electromagnetic pollution to society because of wide use in various electronic devices. Not only will electromagnetic pollution affect the normal operation of equipment, but also endanger human health. In order to prevent electromagnetic pollution from further deterioration of the electromagnetic environment and doing damage to human health, preparation and development of electromagnetic wave absorbing material has become the hotspot of scientists and engineers focusing on.This paper selected iron silicon alloy flake as the magnetic loss agent, since it has higher permeability, high resistivity, and lamellar structure which eliminates the limitations of Snoek limit, so as to guarantee strong electromagnetic performance; Carbon fiber, which is widely used in toughening material mechanics as a representative of the engineering fiber, has also a high electrical conductivity, chemical stability and low density, as a type resistance loss absorbing materials for preliminary study. This paper will be two different loss mechanism of the alloy sheet magnetic powder and carbon fiber composite, with paraffin as the matrix.we prepared the carbon fiber/Fe Si Al, carbon fiber/Fe Si Cr composite absorbing material, respectively. Magnetic powder particle size distribution is analyzed by laser particle size analyzer, the phase composition of magnetic powder is studied by X-ray diffraction(XRD) analysis, the morphology of magnetic flake and carbon fiber is recorded by scanning electron microscope. We also obtain composite complex permittivity and complex magnetic permeability through the vector network analyzer, and calculate the reflectivity of composites to represent absorbing properties of materials according to the transmission line equivalent theory.The experimental results show that:(1) Fe-Si alloy powder absorbing agent within 0.2 GHz~2.6 GHz are presented reflectivity peak, with the increase of the relative contents of paraffin, reflectance peak move to high frequency, reflectivity widened the band width of less than-10 d B.(2) Chopped carbon fiber content and length; Long carbon fiber content, arrangement of segments; Orthogonal arrangement spacing, arrangement of carbon fiber module number will have an effect on composite absorbing performance. When chopped carbon fiber content is 0.4 wt%, composite reflectivity peak reached-49.6 d B, Fe Si Cr/carbon fiber composite materials reflectance peak reached-40.7 d B; When carbon fiber length is 4 mm, Fe Si Al/carbon fiber composite materials reflectance peak reached-38.8 d B, when the carbon fiber length is 6 mm, the reflectivity of Fe Si Al/carbon fiber composite materials the band width of less than-10 d B is 0.92 GHz, which is the widest material absorption bands. When long carbon fiber content is 0.4 wt %, the frequency of 2.6 GHz, the peak reflectivity Fe Si Al/carbon fiber composite materials for-7.6 d B, carbon fiber/Fe Si Cr peak reflectivity of the composite reached its-7.5 d B. Orthogonal arrangement spacing is smaller, the smaller composite reflectivity. With the increase of number of orthogonal configuration module, composite reflectivity is smaller, the better the performance of absorbing.(3) Sheet arrangement orientation of magnetic powder impact on composite reflectivity. When flake magnetic powder parallel arrangement, Fe Si Al absorbing agent in the frequency of 1.75 GHz reflectance minimum value is-44.2 d B, the band width of reflectivity less than-10 d B is 0.5 GHz, Fe Si Cr absorbing agent in the frequency of 1.98 GHz reflectance minimum value is-36.1 d B.(4) When Fe Si Al content, Fe Si Al/Fe Si Cr composites reflectance peaks move to low frequency, and value decreases. When Fe Si Al relative content of 70 wt%, composite material reflectance minimum value of-36.1 d B, absorbing the best performance. |
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