Construction of sandwich-structured Cu-Ni wood-based composites for electromagnetic interference shielding

Constructing a controllable electromagnetic gradient toward advanced electromagnetic interference shielding composites has become a development trend. A sandwich-structured Cu-Ni wood composite (CNWC) was successfully fabricated via a simple electroless Cu-Ni procedure. The obtained results showed that the Cu-Ni wood composite material exhibited excellent electromagnetic shielding effectiveness (EMSE) (average value 57.4 dB) in the entire X-band (from 8.2 to 12.4 GHz) in case of low thickness (0.4 mm) and low density (0.87 g/cm3). Herein, the wood-based composites possessed maximum saturation magnetization which was up to 7.7 emu/g and the conductivity increased to 1930 S/cm. The dielectric loss and magnetic loss are important ways of electromagnetic wave attenuation in Cu-Ni-based electromagnetic shielding materials, and are the key to the absorption of most electromagnetic waves by composites. The electromagnetic gradient sandwich-structure can realize multi-dielectric interface loss and multiple reflection loss. When the electromagnetic wave enters the porous structure inside the wood, the electromagnetic wave generates internal scattering and multiple reflections in the hole. The synergistic effect of dielectric loss and magnetic loss to improve the loss ability of electromagnetic wave.