Effects of reducing agent on microwave absorption properties of HGM/Ni-P core/shell particles

Based on the NaH₂PO₂ as reducing agent, Ni-P layer was deposited on the surface of microspheres by electroless plating, getting the lightweight hollow glass microspheres/Ni-P core/shell particles (referred to as HGM/Ni-P core/shell particles). The phase structures, morphologies, particle size, shell thickness, chemical compositions and the microwave absorbing properties of the core-shell particles have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and vector network analyzer (VNA), respectively. The results showed that with the increaseing of the reducing agent, surface morphology of HGM/Ni-P core/shell particles shows few different, but P content of shell layer increases, and amorphous structure in the shell change, amorphous ingredients increase. The dielectric properties and magnetic permeability of HGM after plating was greatly improved. As the concentration of NaH₂PO₂ increased from 20 to 30 g/L, the resonance peak of ε' and ε″ moved to higher frequency, as the concentration of NaH₂PO₂ got to 40 g/L, the resonance peak disappeared and the dielectric constant reduced. Meanwhile, the fluctuation of μ' and μ″ at 6-8 GHz disappeared as the NaH₂PO₂ increased.