Microwave Absorption Properties of Fe3O4 Particles Coated with Al via Rotating Magnetic Field Method

Soft magnetic composites (SMCs) of Fe3O4 particles coated with Al nanoparticles were prepared using the rotating magnetic field method, and the microwave absorption properties and microstructures of these composites were investigated. The results show that a well-distributed Al nanoparticles coating layer was formed on the surface of the Fe3O4 particles upon mechanical friction and rotating magnetic field distribution. Scanning electron microscopy and X-ray diffraction XRD studies show that the rotating magnetic field method can produce a uniform coating of the aluminium layer on the Fe3O4 particles. Compared with common composites from Fe3O4 particles, SMCs of Fe3O4(Al) particles have stronger magnetic loss behaviour and weaker dielectric loss ability, as well as good reflection characteristics over a wide frequency range. The minimum reflection loss (RL) is −16.2 dB at 12.0 GHz for a corresponding thickness of 5 mm obtained for SMCs of Fe3O4(Al) particles. The presented rotating magnetic field method used in the Fe3O4 particles coating process with Al nanoparticles has great potential in composite materials synthesis with different morphology and areas of application.