Study On Electromagnetic Shielding And Mechanical Properties Of AE45 Layered Structure

The popularization and application of the 5th Generation Mobile Communication Technology(5G)has facilitated people’s production and life,but also brought electromagnetic interference problems.As the most efficient protection method,the research and development of electromagnetic shielding materials is particularly important.As a "green engineering material in the 21 st century",magnesium alloy has the advantages of light weight,good heat dissipation and degradability,as well as special electromagnetic shielding performance,which is a potential electromagnetic shielding material.Therefore,this thesis proposes a method to build AE45 magnesium alloy layered structure material by stacking rolling process to improve its internal electromagnetic wave absorption.Based on the principle of electromagnetic shielding,two ways of increasing electromagnetic shielding performance,namely "endogenous second phase" and "impedance mismatch continuous interface",are studied respectively.Multilayer AE45 and AE45/Mg magnesium alloy layered composites with different configurations were prepared.The microstructure,conductivity,electromagnetic shielding performance and mechanical properties of layered materials with different structural parameters after lamination were tested and analyzed by OM,SEM,XRD,eddy current method and waveguide method.The main research contents and results are as follows:AE45 magnesium alloy plates with different deformation were obtained by multi pass continuous rolling of AE45 magnesium alloy plates.Through testing its microstructure,electrical conductivity and electromagnetic shielding performance,the evolution law of high-frequency electromagnetic shielding performance during the rolling process of AE45 magnesium alloy was analyzed and discussed.After multi pass continuous warm rolling,with the increase of rolling deformation,the electromagnetic shielding performance decreases in the X-band,and the mechanical properties increase.When the rolling deformation is 50%,the electromagnetic shielding effectiveness is96.71 d B-111.89 d B,and the average shielding effectiveness is 103.69 d B.Layered AE45 magnesium alloy was prepared by accumulative roll stacking and multi-layer single pass roll stacking.The influence of the roll stacking process on the microstructure and electromagnetic shielding effectiveness of layered AE45 magnesium alloy was studied,and the mechanism of the influence of different layered structure and precipitation phase distribution on electromagnetic shielding performance was revealed.The research results show that the large deformation warm rolling process will cause the dynamic precipitation of the second phase.On the one hand,the precipitation of the second phase will reduce the lattice distortion and improve the conductivity.On the other hand,under the action of shear stress,the formation of a banded distribution of the second phase will enable electromagnetic waves to circulate and reflect in the "shielding belt",thus enhancing the shielding effect on electromagnetic waves.After three passes of stacking,the electromagnetic shielding efficiency in the X-band range will reach 95.18 d B-110.45 d B.AE45/pure Mg layered structure is constructed to make full use of layer interface reflection caused by impedance difference of adjacent layers.The layered structure of composite materials is controlled by controlling the stacking pass and the combination mode of stacking plates.Because of the difference of plastic deformation ability between AE45 magnesium alloy and pure magnesium,and the difference of impedance between AE45 magnesium alloy and pure magnesium,the electromagnetic wave attenuates due to the cyclic reflection at the interface.The arrangement of AE45/AE45/pure Mg/AE45/pure Mg/AE45/AE45 is used for multi-layer rolling.In the X-band range,the electromagnetic shielding effectiveness is the best,94.47 d B-109.34 d B,and the average shielding effectiveness is 100.59 d B.At the same time,the mechanical properties are the best,the tensile strength is 316.3MPa,the elongation is20.4%,and the surface hardness is 106 HV.