Electromagnetic shielding performance of Nickel plated expanded graphite/wood fiber composite

To develop a wood-based electromagnetic shielding composite, in-situ electroless plating was used to plate nickel onto the surface of expanded graphite (EG) to obtain nickel-plated EG (Ni-EG), and the Ni-EG was mixed with wood fiber to manufacture the composite. The optimal plating formula was as follows: 20 g/L NiSO4·6H2O as the main salt, 60 g/L N2H4·H2O as the reducing agent, 50 g/L Na3C6H5O7·2H2O as the complexing agent, 40 g/L CH3COONa·H2O as the buffering agent, pH value 11, and a temperature of 90 °C. These conditions yielded the highest quality of nickel coating (3.57 g). As EG concentration increased from 2 to 10 g/L, the percentage of the Ni-EG in the composite was 60%, the thickness of the composite was 2 mm, the density was 0.9 g/cm3, the magnetic properties and resistivity of the Ni-EG decreased from 29.5 to 5.57 emu/g and 80.2 to 10.7 mΩ·cm, respectively, and the electromagnetic shielding effectiveness (SE) and the reflectivity of the composite increased from 55 to 60 dB and -3.6 to -1.8 dB, respectively. Consequently, the introduction of nickel is suitable for improving the absorbing performance of Ni-EG/wood fiber composites, leading to better SE in a broad frequency range.