Electrical and shielding properties of ABS resin filled with nickel-coated carbon fibers

Electrical conductivity and shielding effectiveness of nickel-coated carbon fibers and their composites have been studied and the results are presented in this paper. A continuous electroplating device was used to plate nickel over the surface of the carbon fibers. The resistivity of Ni-coated carbon fibers decreases with an increase in plating time. The optimum thickness of the coating is 0.2-0.5 mu m. A solvent method and Brabender mixing were used to prepare the composites of Ni-coated carbon fibers in ABS resin, the resistivity of which decreases with an increase in fiber content. At the same fiber content, the conductivity of the composites filled with Ni-coated carbon fibers is much greater than that of ordinary carbon-fiber-filled composites. To reach the same resistivity as carbon-fiber-filled composites, the use of Ni-coated carbon fibers as filler can greatly decrease the required volume fraction of fibers. The shielding effectiveness of the composites was obtained by experiment and by theoretical calculation; at high frequencies, the two correspond very well. From experimental measurement, the shielding effectiveness of ABS resin filled with 10 vol.% of Ni-coated carbon fibers is about 50 dB.