Preparation and microwave-absorbing properties of hollow glass microspheres double-coated with Co–Ni/Fe3O4 composite

Abstract

Hollow glass microspheres (HGMs) double-coated with Co–Ni/Fe3O4 composite has been successfully prepared by electroless plating and coprecipitation method, which is applied to the microwave absorption materials. The surface morphology, structure, magnetism, electromagnetic property of the products have been characterized by scanning electron microscope, X-ray diffraction, vibrating sample magnetometer and vector network analyzer, respectively. The results show that the outer surfaces of HGMs were coated by continuous and uniform layers of Co–Ni/Fe3O4. The maximum magnetization and coercivity values of HGMs/Co–Ni/Fe3O4 composite increase to 19.46 emu/g and 505 Oe, with a maximum applied magnetic field of 10 kOe. The dielectric loss and magnetic loss of the composite increase remarkably in the frequency range of 1–18 GHz. The maximum microwave reflection loss could reach −35.4 dB at 6.7 GHz (C-band) with 1.81 GHz bandwidth below −10 dB.