Preparation and microwave absorption properties of ferrite/ reed charcoal composites

In order to solve the problems of high density and narrow absorption bandwidth of ferrite absorbing materials, the ferrite/reed charcoal (Ferrite/RC) composites were prepared from reed stalks by impregnation and high temperature in-situ growth methods. The electromagnetic characteristics and electromagnetic wave absorption properties of the composites were controlled by tailoring the carbonization temperature. The results of SEM, TEM, XRD, and VNA showed that the Ferrite/RC composites retained the natural three-dimensional honeycomb network structures of the reed stalks, and Fe₃O₄ and iron nanoparticles were uniformly distributed in the charcoal wall and pores of the reed stem; Raising the carbonization temperature (650~690℃) can increase the conductivity and dielectric loss ability of composites, but excessive temperature can lead to impedance mismatch of the material and reduce its electromagnetic attenuation ability. The composites prepared at a carbonization temperature of 670℃ exhibit the best absorption performance, with a reflection loss of -45.7 dB at a thickness of only 1.7 mm and an effective absorption bandwidth of 5.7 GHz (12.1-17.8 GHz) at a thickness of 2 mm, which is attributed to the good conductivity loss, polarization relaxation, and the synergistic effect of electrical and magnetic losses of composite materials. The excellent absorption performance of Ferrite/RC composites has good prospects in the field of electromagnetic wave absorption, which can promote the high-value and functional application of reed resources.