Study On The Preparation And Microwave Absorption Properties Of Corrosion Resistant High Entropy Oxides (Fe,Co,Ni,Cu,M)Cr_xO_y(M=Mg,Zn)

With the rapid development of 5G mobile communication technology and new electronic components,the problem of electromagnetic wave pollution has attracted more and more extensive attention from scholars at home and abroad,and electromagnetic waves can cause serious interference to the normal work of electronic devices.Therefore,in order to eliminate the interference or harm caused by electromagnetic waves to electronic components,human body,environment,etc.,it is imperative to develop new wave absorbing materials.In order to achieve the comprehensive requirements of"thin,light,wide and strong"and corrosion resistance for the new electromagnetic wave absorbing materials,the complex phase high entropy oxide absorbing materials are born.In this thesis,research on the design,preparation and modulation of electromagnetic wave absorption properties of new high-entropy oxide wave absorbing materials is carried out.The main research in this paper is as follows:FeO,CoO,NiO,CuO,ZnO,MgO,Cr₂O₃ raw materials were used to configure the raw materials according to the molar ratio of the chemical formula(Fe_0.2Co_0.2Ni_0.2Cu_0.2M_0.2)Cr₂O₄（M=Mg,Zn）.（Fe,Co,Ni,Cu,Mg）Cr_xO_yand（Fe,Co,Ni,Cu,Zn）Cr_xO_y complex-phase high-entropy oxide materials of spinel and perovskite structure were successfully prepared by solid-phase reaction sintering under air atmosphere.The materials were tested by vector network analyzer and other equipment,and the wave absorption mechanism and corrosion resistance of the two high-entropy oxides were analyzed.The waveguide method was chosen to test the best wave absorption performance of（Fe,Co,Ni,Cu,Mg）Cr_xO_y and（Fe,Co,Ni,Cu,Zn）Cr_xO_y prepared at 1300℃,Among them,（Fe,Co,Ni,Cu,Mg）Cr_xO_y and（Fe,Co,Ni,Cu,Zn）Cr_xO_y showed strong wave absorption and good morphology after corrosion in different concentrations of HCl,HF and Na OH solutions,and the samples showed good corrosion resistance with little change in quality before and after corrosion.The minimum reflection loss(RL_min)of 3.2 mm thickness of high entropy oxide（Fe,Co,Ni,Cu,Mg）Cr_xO_y bulk sintered at 1300℃can reach-30.7 dB;the maximum effective absorption bandwidth（EAB）of 2.8 mm sample is 3.6 GHz.（Fe,Co,Ni,Cu,Zn）Cr_xO_y blocks,also sintered at 1300°C,were able to achieve a minimum reflection loss(RL_min)of-34.6 dB and a maximum effective absorption bandwidth（EAB）of 2.5 GHz.The experimental results show that both high-entropy oxides have excellent wave absorption and corrosion resistance,and the complex phase structure and component design of the high-entropy oxides can effectively enhance the wave absorption performance of the materials,and they still have strong wave absorption performance after corrosion by different concentrations of HCl,HF and Na OH solutions.In this paper,the wave absorption performance of high entropy oxides is adjusted by component design and phase design,and the effects of synergistic effects such as dielectric loss,interfacial polarization,dipole polarization,magnetic loss,eddy current loss,and natural exchange resonance on the wave absorption performance of high entropy oxides are investigated,and the corrosion resistance of high entropy oxides is explored.It is shown that the high-entropy oxides studied in this paper have a broad practical application prospect in comparison with other traditional wave absorbing materials.The modulation of components and crystal structure enables the high-entropy oxides to obtain excellent wave-absorbing properties and corrosion resistance,which provides a valuable reference for the design and preparation of new wave-absorbing materials.