Electromagnetic Shielding Effectiveness of Nickel Fiber-Reinforced Cement Composites

Abstract

The nickel fiber was added into the cement-based composite materials as a shielding medium. Influences of the three different types and amount of dispersants and weight fraction of nickel fiber on the electrical conductivity and electromagnetic shielding effectiveness of the cement matrix composite were discussed. The conductivity of cement based composite materials and the uniformity distribution of shielding medium were characterized by four-point probe meter and scanning electron microscopy, respectively. Electromagnetic interference shielding effectiveness in the frequency range of 1 MHz to 1500 MHz was characterized by coaxial cable method. The results indicated that the improved dispersion of nickel by incorporation of dispersants might yield the enhancement of the electrical properties of nickel fiber-reinforced cement composites. When the dosage of methyl cellulose reaches 0.4 wt.%, the pre-dispersing nickel fiber enhances the electrical conductivity of the cement-based composite materials significantly. With the increase of fiber volume fraction, the shielding effectiveness and trend of frequency change of the corresponding fiber-reinforced concrete were enhanced. When the content of nickel fiber powder was 9.0 vol.%, the conductivity was 2.65×10-3 s·cm-1, and the average shielding effectiveness of the specimen in 1MHz-1500 MHz was about 21.78 dB, with the maximum shielding effectiveness of 24.48 dB and the minimum shielding effectiveness 19.85 dB.