Research On Magnetic Metal/Graphene And Magnetic Metal Composite Absorbing Materials

The flaky magnetic metal has electromagnetic properties of high dielectric permittivity and high magnetic permeability,which can be widely used in the absorbing materials field by exceeding the Snoek limit.As a new two-dimensional material,graphene has become a research hotspot in the field of absorbing materials.Wherefore the composite absorbing materials in which magnetic metal is doped with Graphene Oxide(GO)and reduced graphene Oxide(RGO)have been prepared,and the morphology,structural characteristics,electromagnetic parameters and absorbing properties of the composites are also studied under different processes(ball milling time and coupling agent).On the other hand,the absorbing properties of Carbonyl Iron Powders(CIP)and FeSiAl composites were investigated based on the dielectric regulation mechanism.The main research contents are as follows:(1)The composites of carbonyl iron/GO and FeSiAl/GO were prepared by combining GO with magnetic metal.The SEM results show that GO has a undulating sheet structure,and the magnetic metal and GO composites exhibit a typical flaky-like structure after ball milling process.The addition of a coupling agent can make the particles smoother and more dispersed.XRD results indicated that all samples exhibited a single ?-Fe phase.The results of FTIR spectroscopy indicated that the functional groups in the carbonyl iron/GO composite did not change significantly under different processes.Compared with a single magnetic metal,absorbing properties of magnetic metal and GO composites have significantly improved.At the thickness of 1.5 mm,the carbonyl iron/GO composite sample with 1 h ball milling time and without the coupling agent had a minimum reflection loss of-10 dB at 4.2 GHz.The FeSiAl/GO composite sample with 1 h ball-milling time and coupling agent had a minimum reflection loss of-9.7 dB at 3.5 GHz.The reflection loss peak of each sample gradually shifted to the low frequency as the ball milling time increased.(2)The environmental friendly vitamin C is used as a reducing agent,and the GO is reduced to prepare RGO.The composite absorbing materials of magnetic metal(carbonyl iron,FeSiAl)and RGO was prepared by ball milling method in the same manner as described above.The SEM results show that the magnetic metal and RGO composite have a sheet structure.XRD results showed that GO was reduced to some extent,and all samples also exhibited a single ?-Fe phase.At the thickness of 1.5 mm,the minimum reflection loss peak of the carbonyl iron/RGO composite with 1 h balling time and without coupling agent reached-11.5 dB at 5.5 GHz.The minimum reflection loss of FeSiAl/RGO with 1 h balling time and with coupling agent at 3.5 GHz was-9.3 dB.The reflection loss peak of each sample also gradually shifted to the low frequency as the ball milling time increased.(3)The ball-milled carbonyl iron powder and FeSiAl were ultrasonically mixed in different proportions,and dielectric regulation of composite absorbing materials by different components to prepare carbonyl iron/FeSiAl composite applied for S-band.The SEM results show that the carbonyl iron/FeSiAl composite has a sheet structure.The EDS Mapping results show that the main element contained in the composite is iron.FTIR spectroscopy results indicate the presence of carbonyl groups in the composite.When the mass ratio of carbonyl iron to FeSiAl is 1:4,the minimum reflection loss of the composite reaches 6.4 dB at 2.3 GHz,and the bandwidth with reflection loss less than-5 dB can reach 2.3 GHz.By adjusting different components,the composite absorbing materials applied for S-band with different absorbing properties can be obtained.