Preparation And Properties Of Structural Absorbing Materials Based On 3D Printing

Absorbing materials play an important role in aerospace,military weapons,radar,construction and electronic products.However,the single-loss-mechanism absorbent and radar absorbing coating are difficult to meet the requirements of strong absorber performance,wide frequency band,light weight,thin structure and good environmental adaptability.Based on the electromagnetic parameters of the material,numerical simulation method is used to design and optimize the absorbing structure to realize the coupling between the material and the structure.3D printing technology is applied to prepare the structural absorbing material with multiple advantages such as peak value and broadband.Firstly,the preparation technology of absorbing material with multi-loss mechanism is studied.Carbon black and carbonyl iron powder were selected as dielectric loss absorbers and magnetic loss absorbers respectively,and the effects of the mixing amount of carbon black and carbonyl iron powder on the electromagnetic parameters of the material and the absorber performance of the coating were studied by using vector network analyzer.The results show that when the coating thickness is2 mm,the carbon black content is 4%(mass ratio,relative to epoxy resin matrix,the same below),and the carbonyl iron content is 250%,the absorber performance of the material is the best.The absorptivity of the material is more than 90% in 9-18 GHz,and the peak value is about 12.5 GHz,up to-40 d B.Then,the absorbing structure is designed and optimized based on the optimal material formulation.CST simulation software is used to scan the parameters of commonly used honeycomb,pyramid,laminates and self-designed composite prisms to explore the influence of structural parameters on the absorber performance.The results show that the absorber performance of honeycomb structure is better than that of flat structure,and the mass is lighter.The absorber performance of laminates at vertical incidence is better than that of single-material plates,but the oblique incidence is only 28% of the vertical incidence bandwidth.The bandwidths of the pyramid and the combined prism are between 11 and 13 GHz.The bandwidth of the pyramidal structure is slightly better than that of the combined prism structure,which is 12.9 GHz.However,the performance loss of the combined prism structure is small under the condition of oblique incidence,and the bandwidth of the combined prism structure can reach 88% of the vertical incidence.Finally,the structural absorbing materials are fabricated by direct and indirect 3D printing methods.By controlling printing speed,air pressure,temperature and other parameters,and adjusting the fluidity and thixotropy of materials,the honeycomb structure is made by direct writing 3D printing technology.Using FDM printing mold,the pyramid structure and composite prism structure are made indirectly.The experimental results are in good agreement with the simulation results by using the bow method to measure the reflectivity of different structures.In this paper,a structural absorbing material with multiple loss mechanism is prepared,and the influence of material and structural parameters on its absorbing properties is revealed,which has reference value for the study of new high performance absorbing materials.