Nickel and silver coated nano-SiO₂ with excellent conductivity and permeability

Considering the importance of electromagnetic shielding fillers in the advanced electromagnetic shielding material and the shortcomings of the current fillers in electrical and magnetic conductivity properties, a facile two-step electroless plating process, including coating nickel layer onto nano-SiO₂ followed by coating another Ag layer onto SiO₂/Ni obtained, was developed to fabricate electromagnetic shielding fillers in this study. The effects of SiO₂ loadings on the thickness, density, magnetic permeability and electric conductivity of as obtained SiO₂/Ni/Ag fillers have been investigated completely. The results indicated the thickness of Ni and Ag layer could be finely tuned by changing the content of SiO₂ and SiO₂/Ni during electroless plating processes. The optimised SiO₂/Ni/Ag nanocomposites demonstrate high magnetic permeability and excellent electrical conductivity with 1·60×10^-5 H m and 1·82×10^-5 Ω m respectively. This method provides a facile and low cost strategy to fabricate nano-fillers for the polymer based electromagnetic shielding composite materials.