Synthesis And Microwave Absorption Properties Of Graphene/Zeolite Nanocomposites

The rapid development of electronic technology has brought convenience to human life, but the impact of electromagnetic radiation on the environment is also increasing. Therefore, absorbing material has become one of the key areas of research in the field of electromagnetic materials. Furthermore, the development of new absorbing materials with "thin thickness, wide frequency band, light weight and strong absorption" has become a promising trend in this field. In this thesis, we designed and prepared a complex wave absorbing material composed mainly by zeolite and graphene by realizing the unique electromagnetic properties of graphene and special framework of zeolite. The absorbing capacity of the materials has been tested in the frequency range of 2-18 GHz. The influence of the morphology of the zeolite and graphene content on the absorption properties of the materials was studied based on experimental results, and then the absorbing mechanism of the materials was discussed. The main results are summarized as follows:（1） Investigated the absorbing properties of target composite materials, which is a combination of graphene and zeolite（NaA） with different states and different treatment procedures. Among the resulting materials, m-rGO and NaA resulting composite material is found with excellent absorbing properties, and considered as a dielectric loss absorbing material.（2） Prepared Fe₃O₄/NaA/m-rGO ternary absorbing material which is an electrically loss absorbing material. Such material is demonstrated with strong absorbing properties at low frequency, as well as an effective absorption bandwidth of 4.0 GHz in high frequency.（3） Investigated the role of zeolite materials and their morphology in the composites materials and made comparison with composites materials without zeolite component. The results showed that the incorporation of zeolite NaA not only improved the EM absorption intensity, but also enlarged the bandwidth of reflection loss values below-10 d B. And the zeolite exhibits two forms: nano-particles and well-crystallized, which ensure the graphene layers to be well dispersed.（4） Investigated the effect of the content of graphene in composites on absorbing properties, and studied the structure and properties of different components of the composite materials. The results showed that the composite materials with three different ratios have good absorbing properties. Along the m-rGO content increasing, it is found that the absorption is first enhanced followed with a recession and the absorption peak shifts from the low frequency band to the high frequency. It shows that the components gives an excellent EM wave absorption performance at a ratio of Fe₃O₄:NaA:m-rGO=1:9:10.The maximum absorption is-60.3 dB at 6.72 GHz and the reflection loss values are less than-30 dB with thickness of 2.0-5.5 mm over 3.9-18 GHz.The study shows that this brand new fully inorganic absorbing material has the characteristics of light weight, wide frequency band and strong absorption, thus, the materials is considered with broad application prospects in the future military and civil fields.