Shielding effectiveness of high-permeability porous foamed metals

Open celled porous metal foam, with its advantages of highly uniform structure and continuously overlapping regular distribution of its pores, excellent permeability and electrical conductivity, is widely used in varieties of ventilating and cooling devices in electronic equipment to achieve electromagnetic reinforcement. In this paper, the process of producing open celled nickel foam with high permeability by deposition method is introduced. After the conductivity and shielding effectiveness test, the results demonstrate that porous foamed nickel had good conductivity at porosities, greater than 95%, reaching 10⁵ S/m; It performed good shielding effectiveness over a wide frequency range, at 25 dB (10 kHz), 87 dB (15 MHz), 46 dB (18 GHz), etc. respectively. Furthermore, based on the characteristics of the 3D network skeleton construction of most of the same pores of porous nickel foam, the basic dodecahedron-structure unit model for electromagnetic transmission is established by using 3D model method. Meanwhile, the shielding mechanism of porous nickel foam is discussed, which provides guidance for the application of highly permeable metal foam materials in electromagnetic protection.