Excellent microwave absorption property of nano-Ni coated hollow silicon carbide core-shell spheres

Using yeast as a template, hollow silicon carbide spheres (HSS) with complete morphology and uniform dispersion were prepared by sol-gel method followed by a carbon thermal reduction method. Thin films composed of Ni nanoparticles (NPs) were uniformly coated onto the hollow silicon carbide spheres by Pd activated alkaline electroless plating technique. Finally, a novel microwave absorbent Ni NPs coated hollow silicon carbide spheres (Ni@HSS) was obtained. A variety of modern characterization methods were used to study the crystal structure, microstructure, element composition, electromagnetic performance and microwave absorption performance. It is found that the Ni@HSS structure possess excellent microwave absorbing properties. For instance, at the frequency band of 2-18 GHz, the maximum reflecting loss of -50.75 dB can be obtained at the absorber layer thickness of 4.2 mm. When the absorbing layer thickness is 3.6 mm, the effective absorption bandwidth of 9.31 GHz can be realized. Last but not the least, the mechanism of improved microwave absorption performance of Ni@HSS is discussed in detail on the basis of its structure, morphology and electromagnetic characteristics.