Electromagnetic Shielding Effectiveness of Cement-matrix Composite Containing Nickel Fiber

摘要

The cement-matrix composite with the function of building structure and electromagnetic interference shielding was prepared by filling nickel fiber into cement. The dispersion of nickel fiber in cement-matrix composite and the shielding effectiveness of composite containing various volume fractions of nickel fiber were investgated in this paper. The electromagnetic interference shielding effectiveness in the frequency range of 0.1 MHz to 1.5 GHz and the conductivity of composite were measured by coaxial cable method and two-probe method,respectively. The dispersion of nickel fiber in cement was characterized by EPMA. The results indicated that the dispersion property of nickel fiber by sodium hexametaphosphatecan was better than sodium carboxymethylcellulose. The optimum contents of nickel fiber in composite was 5 voL%,the maximum shielding effectiveness was 45.7 dB in 140 MHz and the minimum shielding effectiveness was 36 dB in 1240 MHz. The shielding effectiveness of composite with 7 vol.% nickel fiber was lower than that with 5 vol.% nickel fiber due to the tendency of nickel fiber cling to each other.