Search

The surface coating of magnetic nanoparticles onto hollow glass microspheres (HGMs) is of vital importance as light-weighted powders with wave-absorbing properties. In this study, HGMs were successfully coated by Co/Ni nanoparticles through a four-stepped strategy of NaF + HCl roughening, NaOH washing, PdCl2 activation, and electroless plating, successively. The soft roughening of SiO2 with NaF and the post-washing of Na2SF6 byproducts with NaOH were validated to ensure the integrity of the as-coated HGMs. The Ni–Co–P alloy coatings were measured to be lower than 1 μm in thickness with nanoparticles of 100–200 nm in diameter. The reflection loss of HGMs coated by 30 wt% Ni/Co not only retained the peak of the Co coating (− 4.5 dB) but also reached about − 6.7 dB at 16.4 GHz, much higher than that of HGMs coated by Ni and Co. The overall trend of input and output impedance ratio of the sample coated by Ni/Co does not change significantly compared with HGMs coated by Co, but the impedance matching has been optimized compared with Ni-plated powders. The novel light material with a uniform and complete coating prepared in this paper provides a new idea for the modification of HGMs for multi-functional applications. [ABSTRACT FROM AUTHOR]