Preparation And Absorbing Properties Of Nickel-based Metal Modified Graphite Nanosheet Composites

Traditional single-type absorbing materials are no longer suitable for use in contemporary electromagnetic wave pollution environments.The combination of various absorbing materials to form a new composite material has the advantages of multiple absorbing mechanisms,has stronger absorbing ability,and can adapt to various complex environments.It is the main research direction of contemporary absorbing materials.Graphene,which has excellent electrothermal properties and mechanical properties,is a hotspot in today's materials research.The high conductivity of graphene makes it theoretically a absorbing material with great potential.Combining it with a magnetic metal material with a large magnetic permeability can improve the impedance matching of graphene and make a variety of loss mechanisms work synergistically.It is a promising absorbing material.In this paper,Ni-based magnetic metals and alloys were reduced and grown on graphite nanosheets prepared by physical method using one-step hydrothermal method.The effects of process conditions(component composition,hydrothermal temperature and hydrothermal time)on the morphology and absorbing properties of the materials were investigated to screen out the optimal absorbing properties.The hydrothermal temperature and hydrothermal time have a positive correlation with the microscopic dimensions of the Ni-based of magnetic metals and alloys.During the experiment,it was found that Fe is more difficult to deposit than Ni.In Ni-Fe-P alloy,the composition ratio of Ni and Fe cannot be flexibly controlled,while the deposition efficiency of Co and Ni is similar,and the composition ratio of Ni to Co can be flexible controlled in Ni-Co-P alloy.Therefore,the effects of composition on the morphology and absorbing properties of Ni-Co-P alloy/graphite nanosheets are discussed in detail in this thesis.It is found that in Ni-Co-P alloy,Ni promotes crystal nucleation and Co promotes crystal growth.The minimum reflection loss of Ni-Co-P alloy/graphite nanosheets under the optimal process of the three Ni-based magnetic metal modified composites is the smallest,with a minimum reflection loss of-57.8 d B at a thickness of 1.5 mm;The optimum absorption bandwidth of Ni-Fe-P alloy/graphite nanosheets is the widest,reaching 5.0 GHz at a thickness of 1.5 mm.The deposition mechanism of magnetic metals and alloys is discussed from the perspective of thermodynamics and kinetics.The degree of deposition of Fe,Co and Ni,was analyzed thermodynamically.Due to the higher reduction potential of Ni,it is the easiest to deposit.The reduction potential of Fe is the lowest,the reduction driving force is very low,and the most difficult to deposit.The deposition difficulty of Co is between Ni and Fe.When Co and Ni are present simultaneously,Ni promotes grainnucleation,Co promotes grain growth.The kinetics explain the phenomenon that magnetic metals and alloys become larger as temperature and time increase.