Microwave absorption of electroless Ni–Co–P-coated SiO2 powder

Ni–Co–P-coated SiO2 particles were prepared using electroless plating method. The morphology, crystal structure, surface compositions, magnetic and microwave absorption properties of the composite powder were investigated by scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, vibrating sample magnetometer and vector network analyzer, respectively. It was found that the silica powder was successfully coated with Ni–Co–P alloy. The ultrafine Ni–Co–P–SiO2 powder-paraffin wax composite possesses excellent microwave absorption properties. The maximum microwave loss reaches −48.6 dB at 4.2 GHz with a thickness of 3.10 mm. The intrinsic reasons for microwave absorption were also investigated.