Preparation And Microwave Absorbing Properties Of Carbonnanotubes/Ferrites Hybrid Buckypaper

As a portion of environmental science and military technology, the electromagnetic wave absorbing materials have become an emerging issue and received more and more attention in the field of high technology. Traditional microwave-absorbing materials, such as spinel-type ferrites and the coating layers of metal powder, are currently the most common and important microwave absorbing materials. They have been extensively researched because of their strong magnetic loss and absorption. However, their high density and single loss mechanism restrict their use in application requiring lightweight materials. Preparing composite microwave-absorbing materials with different structural material is one of the most effective way to overcome this problem and the composites exhibit the advantages of strong absorption, wide frequency range and seclecting dexterity. In this paper, the CNTs were pretreated and activated firstly. Then, the composite absorbers of the multi- walled carbon nanotubes coated with cobalt- nickel metal?MWCNTs/Co-Ni? and the multi- walled carbon nanotubes double-coated with cobalt- nickel metal and Fe₃O₄ particles?MWCNTs/Co-Ni/Fe₃O₄? were prepared successfully by electroless plating and coprecipitation method. Furthermore, the MWCNTs/Co-Ni/Fe₃O₄ composite absorber was added into the process of preparing buckypaper as a certain mass ratio. Finally, the CNTs/ferrite hybrid buckypaper was successfully prepared by vacuum filtration method, whose magnetic loss increased significantly. The resulting products were characterized by scanning electron microscope?SEM?, energy dispersive spectrometer?EDS?, X-ray diffraction?XRD?, fourier transform infrared spectrometer?FTIR?, vibrating sample magnetometer?VSM? and vector network analyzer. The microwave-absorbing and magnetic properties of MWCNTs/Co-Ni, MWCNTs/Co-Ni/Fe₃O₄ and CNTs/ferrite hybrid buckypaper were mainly discussed in this paper.Results indicate that the magnetic and microwave-absorbing properties of all samples increased obviously. The saturation magnetization and coercivity values of MWCNTs/Co-Ni composite absorber are 51.8 emu/g and 221.08 Oe, respectively and the maximum reflection loss is-15.92 dB at 8.65 GHz with 2.8 GHz bandwidth below-10 dB and 4.42 GHz bandwidth below-5dB. The saturation magnetization value of MWCNTs/Co-Ni/Fe₃O₄ composite absorber reaches to 68.6 emu/g and the coercivity value decreased to 17.9 Oe. At the same time, the maximum reflection loss shifts to lower frequency at 8.56 GHz?X- band? with 2.7GHz bandwidth below-5 dB and new absorption peak of reflection loss is detected at 1.51 GHz with the maximum reflection loss of-13.57 dB and 1.05 GHz bandwidth below-5 dB. In addition, the saturation magnetization and coercivity values of CNTs/ferrite hybrid buckypaper are 21.21 emu/g and 32.07 Oe, respectively. There are two continous absorption peaks appearing at 8.64 GHz and 8.95 GHz with the maximum reflection loss of-20.1 dB and-14.38 dB, respectively. The bandwidth below-10 dB can reach 0.72 GHz. Apart from, the absorption peaks is detected at 9.77 GHz with the maximum reflection loss of-12.26 dB and 0.441 GHz bandwidth below-10 dB.