In order to manufacture microwave absorbers with strong attenuation abilities and that are light weight, in this paper, ferromagnetic carbon matrix composites were prepared by the composite of carbon nanotubes with adjustable dielectric constant and Fe3O4. Fe3O4/MWCNT composites with well-designed necklace-like structure and controllable size in the range of 100-400 nm have been successfully achieved by a simple solvent thermal method. A series of samples were prepared by changing experimental parameters. The microwave absorption characteristics of these samples were studied from the dielectric constant and magnetic permeability in two aspects. The electromagnetic absorption properties of the composites show obvious differences with different microsphere sizes, different microsphere density and different proportion of additives. When the solvothermal time is 15 h and the microsphere size is 400 nm, the reflection loss reaches -38 dB. The interfacial polarization caused by the unique structural design and good impedance matching produce composites that possess excellent electromagnetic loss ability.
Keywords: carbon nanotube; composite materials; double loss mechanism; interfacial polarization; microwave absorption; necklace-like structure.