Study On Fused Deposition Molding And Properties Of Graphene Absorber With Laminated Absorber

With the continuous development of wireless communication,electronic equipment and(GHz)digital system working in gigahertz,human living space is filled with electromagnetic waves of different wavelengths and frequencies.Electromagnetic pollution has become one of the public pollution of society,which not only affects the normal operation of electronic equipment,but also may threaten human biological system.In order to solve this problem,people have been devoting themselves to exploring efficient microwave absorbing materials,which can convert microwave into heat or be absorbed by interference dissipation.The ideal and efficient microwave absorbing material should have the characteristics of strong absorption,wide absorption band,light weight,thin matching thickness and so on.On the basis of previous research,the samples with different combinations of FDM process parameters were printed out with the self-made graphene/PLA composite wire,and the best combination of printing process parameters was determined.Combining the influence of different graphene contents on the electromagnetic parameters of single-layer homogeneous samples and the 1/4?theory,a graphene/PLA three-layer absorber was designed,FDM is used to prepare and characterize and test its micro-morphology and electromagnetic properties.in order to further improve the absorbing performance and absorption bandwidth,the absorbers and impedance matching characteristics of graphene/Fe₃O₄/PLA three-layer absorbers and three,six and nine-layer impedance graded absorbers are prepared on the basis of three-layer graphene absorbers,respectively,and the absorbing effects before and after the experimental improvement are compared.The main results are as follows:1.In the process analysis and optimization experiment of warping deformation of graphene/PLA composites in melt deposition molding,when the sample size is small and the warping deformation is taken as the main factor to consider the quality of the printed sample,the delamination thickness has the greatest influence on the warping deformation,followed by the printing speed,followed by the bottom plate temperature,and the nozzle temperature has the least influence.The optimal combination of process parameters obtained by orthogonal experiment is as follows:printing layer thickness 0.1mm,printing speed20mm,base plate temperature 55?,sprinkler temperature 175?.When the same model is printed by using the optimal combination of printing parameters,the average warping of the sample is 0.12mm,and the dimensional accuracy is greatly improved.2.The single-layer homogeneous graphene composite samples were rapidly prepared by melt lamination technology,the effect of different graphene content on its electromagnetic parameters was studied,and the wave-absorbing effect was calculated and analyzed based on the transmission line theory.The composite wire with low graphene content was selected as the transparent layer material,and the composite wire with high graphene content was selected as the absorption layer and the reabsorption layer.The matching thickness range of the absorption layer and the reabsorption layer was determined in the light of the quarter-wavelength matching mechanism.A three-layer wave absorber composed of different graphene/PLA composite wires was designed and manufactured.The test results show that the effect of three-layer absorber is much better than that of single-layer homogeneous absorber,and the best absorbing effect is obtained when the graphene content of the transmission layer,the absorption layer and the re-absorption layer are 5 wt%,7 wt%and 8wt%,respectively.The reflectivity in the 13.3?18 GHz band is less than-10 d B,and the maximum absorption peak is-30 d B at 17 GHz.3.Based on the study of three-layer graphene absorbers.Add a new wave absorbing agent in the absorption layer:Fe₃O₄,the prepared graphene/Fe₃O₄/PLA three-layer wave absorbing body,the effective frequency band reaches 12.8?18GHz,and the absorption peak reaches-30.5d B at 12.5GHz,the composite material effectively expands the frequency band and absorption effect,and the best material layer structure combination is:5wt%graphene,7wt%graphene,15wt%Fe₃O₄,8wt%graphene.certain balance is achieved between the amount of Fe₃O₄ added and impedance matching.The absorber is designed into three,six and nine layers according to the gradual change of impedance.The nine-layer absorber reaches the absorption peak of-20.8d B at 17.4GHz,and the effective absorbing bandwidth is 11.8-18GHz.With the increase of the number of layers,the effective frequency band of the absorber moves to the low frequency band and widens significantly.